Cash Machine

1
Cash Machine

• Harry withdrew the same amount of money from the
  cash point as he had in his pocket. He then spent
  40. He went back to the cash point and again
  withdrew the same amount as he had in his pocket.
  He then spent 50. For the last time he went back
  to the cash point and withdrew the same amount as
  he had in his pocket. He spent 20 and had no
  money left. How much money did Harry start with?

2

• Solution
• Starts with x
• After first withdrawal has 2x
• Spends 40 2x 40
• After second withdrawal has 2(2x 40) 4x 80
• Spends 50 4x -130
• After third withdrawal has 2(4x 130) 8x 260
• Spends 20 and has nothing left 8x 280 0
• 8x 280
• x 35