word problem

Question

ane bought a desktop computer and a laptop computer. Before finance charges, the laptop cost
$250
less than the desktop. She 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
8%
per year. The total finance charges for one year were
$325
. How much did each computer cost before finance charges?

Answer 1

Let's assign some variables

L = cost of laptop

D = cost of desktop

 

From the 2nd sentence, we know

D - L = 250  or D = L + 250

 

Based on the finance charges.

.07D + .08L = 325

 

Using substitution

.07(L+250) + .08L = 325

 

If you multiply the entire equation by 100, you will get rid of the decimals which most people dislike

7(L+250) + 8L = 32500

7L + 1750 + 8L = 32500

15L = 30750

L = 2050

If the price of the desktop was 250 more, then D = 2300