73 Writing TwoStep Equations

1
7-3 Writing Two-Step Equations

• Objective Solve verbal problems by writing and
  solving equations.

2
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12

3
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12 -7

4
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12 -7
• 3m 5 17

5
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12 -7
• 3m 5 17 4

6
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12 -7
• 3m 5 17 4
• (w 3)/7 3

7
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12 -7
• 3m 5 17 4
• (w 3)/7 3 19

8
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12 -7
• 3m 5 17 4
• (w 3)/7 3 19
• (-8 a)/3 6

9
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12 -7
• 3m 5 17 4
• (w 3)/7 3 19
• (-8 a)/3 6 26

10
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12 -7
• 3m 5 17 4
• (w 3)/7 3 19
• (-8 a)/3 6 26
• (r 3)/4 7

11
5-Minute Check

• Solve each equation. Check your solution.
• b 5 12 -7
• 3m 5 17 4
• (w 3)/7 3 19
• (-8 a)/3 6 26
• (r 3)/4 7 31

12
7-3 Writing Two-Step Equations
Example Andy has a history test in a week, but he
is behind in his reading. The test will cover 120
pages in his textbook. He has read only 36 pages.
If he plans to read an equal amount every day of
the week to finish the 120 pages, how much must
he read each day? Explore You know how many
pages andy must read and how many pages he has
already read. You are looking for how many pages
he must read each day for the next 7 days.
13
7-3 Writing Two-Step Equations
Example Andy has a history test in a week, but he
is behind in his reading. The test will cover 120
pages in his textbook. He has read only 36 pages.
If he plans to read an equal amount every day of
the week to finish the 120 pages, how much must
he read each day? Plan Let p the number of
pages read per day.
14
7-3 Writing Two-Step Equations
Example Andy has a history test in a week, but he
is behind in his reading. The test will cover 120
pages in his textbook. He has read only 36 pages.
If he plans to read an equal amount every day of
the week to finish the 120 pages, how much must
he read each day? Plan Let p the number of
pages read per day. Solve 36 pages plus seven
times p pages is 120 pages
15
7-3 Writing Two-Step Equations
Example Andy has a history test in a week, but he
is behind in his reading. The test will cover 120
pages in his textbook. He has read only 36 pages.
If he plans to read an equal amount every day of
the week to finish the 120 pages, how much must
he read each day? Plan Let p the number of
pages read per day. Solve 36 pages plus seven
times p pages is 120 pages 36 7p
120
16
7-3 Writing Two-Step Equations
Example Andy has a history test in a week, but he
is behind in his reading. The test will cover 120
pages in his textbook. He has read only 36 pages.
If he plans to read an equal amount every day of
the week to finish the 120 pages, how much must
he read each day? Plan Let p the number of
pages read per day. Solve 36 pages plus seven
times p pages is 120 pages 36 7p
120 36 7p 120
17
7-3 Writing Two-Step Equations
Example Andy has a history test in a week, but he
is behind in his reading. The test will cover 120
pages in his textbook. He has read only 36 pages.
If he plans to read an equal amount every day of
the week to finish the 120 pages, how much must
he read each day? Plan Let p the number of
pages read per day. Solve 36 pages plus seven
times p pages is 120 pages 36 7p
120 36 7p 120 36 36 7p
120 36
Subtract 36 from each side.
18
7-3 Writing Two-Step Equations
Example Andy has a history test in a week, but he
is behind in his reading. The test will cover 120
pages in his textbook. He has read only 36 pages.
If he plans to read an equal amount every day of
the week to finish the 120 pages, how much must
he read each day? Plan Let p the number of
pages read per day. Solve 36 pages plus seven
times p pages is 120 pages 36 7p
120 36 7p 120 36 36 7p
120 36 7p 84
Subtract 36 from each side. Divide each side by 7.
19
7-3 Writing Two-Step Equations
Example Andy has a history test in a week, but he
is behind in his reading. The test will cover 120
pages in his textbook. He has read only 36 pages.
If he plans to read an equal amount every day of
the week to finish the 120 pages, how much must
he read each day? Plan Let p the number of
pages read per day. Solve 36 pages plus seven
times p pages is 120 pages 36 7p
120 36 7p 120 36 36 7p
120 36 7p 84 p 12
Subtract 36 from each side. Divide each side by 7.
20
7-3 Writing Two-Step Equations
Example Andy has a history test in a week, but he
is behind in his reading. The test will cover 120
pages in his textbook. He has read only 36 pages.
If he plans to read an equal amount every day of
the week to finish the 120 pages, how much must
he read each day? Examine Since 7(12) 36
120, the answer is reasonable. Andy must read 12
pages per day.
21
7-3 Writing Two-Step Equations
Integration Write and solve an equation to find
the length and width of a rectangle if the length
is 8 inches longer than the width and the
perimeter is 40 inches.
22
7-3 Writing Two-Step Equations
Integration Write and solve an equation to find
the length and width of a rectangle if the length
is 8 inches longer than the width and the
perimeter is 40 inches. Let width x. Let
length x 8.
23
7-3 Writing Two-Step Equations
Integration Write and solve an equation to find
the length and width of a rectangle if the length
is 8 inches longer than the width and the
perimeter is 40 inches. Let width x. Let
length x 8. Then we get, 2(x) 2(x 8) 40
24
7-3 Writing Two-Step Equations
Integration Write and solve an equation to find
the length and width of a rectangle if the length
is 8 inches longer than the width and the
perimeter is 40 inches. Let width x. Let
length x 8. Then we get, 2(x) 2(x 8)
40 Solving, we get that x 6 and x 8 14.
25
7-3 Writing Two-Step Equations
Integration Write and solve an equation to find
the length and width of a rectangle if the length
is 8 inches longer than the width and the
perimeter is 40 inches. Let width x. Let
length x 8. Then we get, 2(x) 2(x 8)
40 Solving, we get that x 6 and x 8 14. So,
width 6 and length 14.
26
7-3 Writing Two-Step Equations
Assignment 6 16 even, 18 25 all.