Math CentralQuandaries & Queries


Question from dawn, a parent:


A used book store started selling CDs and videos. In the first week,the store sold 40 used CDs and videos,at 4.00
per CD and 6.00 per video.The sales for both CDs and videos totaled 180.00 she wrote a system of equations to represent the situation.Then she graph the system of equations
Then is asked how many CDs and videos did the store sell in the first week? How would she figure out the answer to how many CDs and videos the store sold the first week.

thanks- Dawn

Hello Dawn,

We need some equations to work with.
Let 'x' be the number of CDs sold, and 'y' be the number of videos sold.

It says that they sold 40 CDs and videos, thus x + y = 40.
It also says sales totaled $180 and that CDs are $4, and videos are $6.
Therefore, we have that 4x + 6y = 180.

We have two equations in two unknowns and can solve for 'x' and 'y'.


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