Lizzy: Mary earns $20 washing cars and $40 walking dogs each month. If she puts half of that money away each month how long would it take her to save $150?.
Me: Hmmm, let me think. I think this is the detailed solution:
Each month she makes 20 + 40 = $60. Every month she saves 60 / 2 = $30. To save $150 it will take her 150 / 30 = 5 months. Final answer: 5.