Question

Jake made a total of 7 copies at a copy shop, with some being black-and-white copies and some being color copies. Black-and-white copies cost 8 cents, and color copies cost 15 cents. If Jake spent a total of 70 cents on copies, which system of equations can be used to determine the number of black-and-white copies and the number of color copies he made? Assume b is the number of black-and-white copies and c is the number of color copies.
b + c = 7. 8 b + 15 c = 70.
b + c = 7. 15 b + 8 c = 70.
b + c = 70. 8 b + 15 c = 7.
b + c = 70. 15 b + 8 c = 7.

Answer 1

To determine the number of black-and-white copies (b) and color copies (c) Jake made, we can set up the following system of equations based on the information provided:

1. The total number of copies made is 7:
\[
b + c = 7
\]

2. The total cost of the copies is 70 cents, where black-and-white copies cost 8 cents and color copies cost 15 cents:
\[
8b + 15c = 70
\]

This leads us to the correct system of equations:
\[
\begin{align*}
b + c & = 7 \\
8b + 15c & = 70
\end{align*}
\]

So, the correct option is:
**b + c = 7. 8 b + 15 c = 70.**