Question

Reuben bought a desktop computer and a laptop computer. Before finance charges, the laptop cost $150 more than the desktop. He paid for the computers using two different financing plans. For the desktop the interest rate was 7% per year, and for the laptop it was 9.5% per year. The total finance charges for one year were $303 . How much did each computer cost before finance charges?

Answer 1

Same case as Pablo's, more or less.

a = price for the desktop

b = price for the laptop

we know the laptop is 150 bucks more than the desktop,  b = a + 150.

how much is 7% of a?  (7/100) * a, 0.07a.

how much is 9.5% of b?  (9.5/100) * b, 0.095b.

total interests for the financing add up to 303, 0.07a + 0.095b = 303.

$\bf \begin{cases} \boxed{b}=a+150\\ 0.07a+0.095b=303\\ ----------\\ 0.07a+0.095\left(\boxed{a+150} \right)=303 \end{cases} \\\\\\ 0.07a+0.095a+14.25=303\implies 0.165a=288.75 \\\\\\ a=\cfrac{288.75}{0.165}\implies a=1750$

how much was it for the laptop?  well b = a + 150.