Question

Carmen bought a desktop computer and a laptop computer. Before finance charges, the laptop cost $200 less than the desktop. She pald for the computers
using two different financing plans. For the desktop the interest rate was 9% per year, and for the laptop it was 7% per year. The total finance charges for one
year were $306. How much did each computer cost before finance charges?

Answer 1

Let x = cost of desktop computer; then x - 250 = cost of laptop computer

converting % to decimals, 9% = 0.09 and 6% = 0.06

Then, 0.09x + (x - 250)0.06 = $300
0.09x + 0.06x - 15 = $300
0.15x = $315
x = $2100
then x - 250 = $1850

Proof: $2100•0.09 + 1850•0.06 = $189 + $111 = $300