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Question 445229: Here's my problem: I don't know how to write an algebraic equation to work this out. Please help, thank you very much.
John bought two computers. One desktop and one laptop. Before finance charges, the laptop cost $1000 more than the desktop. John paid for the computers using two different financing plans. For the desktop, the interest rate was 8.5% per year, and the laptop was 7.5% per year. The total finance charges for one year were $915. How much did the desktop computer cost before finance charges?
Answer by mananth(16946)   (Show Source):
You can put this solution on YOUR website! Laptop x Cost
Desktop ----------y Cost
x-y=1000 .............1
0.075x+0.085y=915 .............2
Eliminate y
multiply (1)by 0.085
Multiply (2) by 1
0.085 x -0.085 y = 85
0.075 x +0.085y = 915
Add the two equations
0.16 x= 1000
/ 0.16
x = 6,250.00
plug value of x in (1)
x-y=1000
6250-y= 1000
-y=1000 -6250
-y=-5250
y=5250.00
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