Lizzy: Sara makes cakes during the five weekdays to sell on weekends. She makes 4 cakes a day and sells her cakes for $8. In 4 weeks she managed to sell all the cakes. How much money did she collect during that time?.
Me: Hmmm, let me think. I think this is the detailed solution:
During the week she makes 5 days / week * 4 cakes / day = 20 cakes. After selling them over the weekend she earns 20 cakes * $8 / cake = $160. In 4 weeks she raised $160 / week * 4 weeks = $640. Final answer: 640.