Answer
$q=-4500p+41,500$
Work Step by Step
We are given data points $(p,q)$
$(3,28000)$ and $(5,19000).$
The line through these points has an equation
$q-q_{1}=\displaystyle \frac{q_{2}-q_{1}}{p_{2}-p_{1}}(p-p_{1})$
$q=\displaystyle \frac{-9,000}{2}(p-3)+28,000$
$q=-4500p+13,500+28,000$
$q=-4500p+41,500$
