SOLUTION: Ravi bought a desktop computer and a laptop computer. Before finance charges, the laptop cost $300 less than the desktop. He paid for the computers using two different financin

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Question 1060529: Ravi bought a desktop computer and a laptop computer. Before finance charges, the laptop cost
$300
less than the desktop. He paid for the computers using two different financing plans. For the desktop the interest rate was
6%
per year, and for the laptop it was
7%
per year. The total finance charges for one year were
$252
. How much did each computer cost before finance charges?

Answer by math_helper(2461) About Me  (Show Source):
You can put this solution on YOUR website!

Let d = cost of desktop
and let a = cost of laptop
--
Write down what we know
a = d - 300 (1)
0.06d + 0.07a = 252 (2)

Eq (1) allows us to substitute "d-300" for "a" in (2):
0.06d + 0.07(d-300) = 252
0.13d - 21 = 252
0.13d = 273
d = 273/0.13 = 2100

Ans:
Desktop cost was $2100
Laptop cost was therefore $1800

Check: 2100(0.06) + 1800(0.07) = 126 + 126 = 252 (ok, finance charges add up)