#### Answer

a. The output of mine #1 over 5 days
b. $
\begin{bmatrix}
150\\2825
\end{bmatrix}
=
x_1v_1 + x_2v_2
$

#### Work Step by Step

a. Since $v_1$ represents the output of mine #1 over one day, multiplying it by 5 yields the output over 5 days.
b. The left hand side shows the desired quantity of copper and silver to be produced, and the right hand side shows the amount that will be produced given a particular number of days of production at mines 1 and 2.