Question

Spiral work

Solve the system of linear

equations for problems 6.
6) A used book store also started selling used CDs and videos. In the first week, the store
sold a combination of 45 CDs and videos. They charged $3 per CD and $7 per video and the
total sales were $187. Determine the total number of CDs and videos sold.
I

Answer 1

32 CDs, 13 Videos

Explanation:

You can represent this question using variables.

Let x = #CDs sold, Let y = #videos sold.

You can formula two equations with the information given:

3x + 7y = 187

x + y = 45

Substitute x into the equation above by reducing the equation below:

x + y = 45 -> x = 45 -y

Since we are now able to remove x from the equation, plug in your new value into the equation above.

3(45-y) + 7y =187

135 - 3y +7y = 187

135 + 4y = 187

4y = 52

y = 13

Knowing the value of y, simply plug in this y value to solve for x:

x + 13 = 45

x = 32