Question

A used book store also started selling used CDs and videos. In the first week, the store sold a combination of 40 CDs and videos. They charged $4 per CD and $6 per video, and the total sales were $180. Determine the total number of CDs and videos sold. Set up a system and solve.

a) CDs = 20, Videos = 20
b) CDs = 10, Videos = 30
c) CDs = 30, Videos = 10
d) CDs = 25, Videos = 15

Answer 1

By setting up a system of equations and using the method of elimination, we find that the store sold 30 CDs and 10 videos. The correct answer is option c) CDs = 30, Videos = 10.

Step-by-step explanation:

To determine the total number of CDs and videos sold by the used book store, let's set up a system of equations based on the information given. Let x represent the number of CDs and y represent the number of videos.

We know that the store sold a combination of 40 CDs and videos, which gives us the first equation:

• x + y = 40

Since CDs are sold at $4 each and videos at $6 each, and the total sales were $180, we get the second equation:

• 4x + 6y = 180

Let's solve this system of equations. First, we can multiply the first equation by 4 to help with elimination:

• 4x + 4y = 160

Subtracting this from the second equation gives us:

• 4x + 6y - (4x + 4y) = 180 - 160
• 2y = 20
• y = 10

Now, substitute y = 10 back into the first equation to find x:

• x + 10 = 40
• x = 30

Therefore, the store sold 30 CDs and 10 videos.