Question

Pablo bought a desktop computer and a laptop computer. Before finance charges, the laptop cost $250 more than the desktop. He paid for the computers using two different financing plans. For the desktop the interest rate was 8.5% per year, and for the laptop it was 5% per year. The total finance charges for one year were $296 . How much did each computer cost before finance charges?

Answer 1

A = price of the desktop

b = price of the laptop

now, we know the laptop was more expensive than the desktop by 250 bucks, thus b = a + 250.

for "a", he paid 8.5% in interest, for "b", he paid 5% in interest.

how much is 8.5% of a?  well (8.5/100) * a, or 0.085a.

how much is 5% of b?  well, (5/100) * b, or 0.05b.

now, we know the total charges for financing were $296, that means the interest paid in total was 296, thus whatever "a" or "b" are, we know that  0.085a + 0.05b = 296.

$\bf \begin{cases} \boxed{b}=a+250\\ 0.085a+0.05b=296\\ ----------\\ 0.085a+0.05\left( \boxed{a+250} \right)=296 \end{cases} \\\\\\ 0.085a+0.05a+12.5=296\implies 0.135a=283.5 \\\\\\ a=\cfrac{283.5}{0.135}\implies a=2100$

how much did the laptop cost?  well, b = a + 250.