Question

Micheal bought a desktop computer and a laptop computer. Before finance charges, the laptop cost $400 less 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 $412. How much did each computer cost before finance charges?

Answer 1

Let's call x the cost of the desktop. So, the cost of the laptop would be x-400 because it costs $400 less than the desktop.

Then, we express the following based on the given information.

$0.085x+0.05(x-400)=412$

Note that we use the percentages as their decimal expression. Let's solve for x.

$\begin{gathered} 0.085x+0.05x-20=412 \\ 0.135x=412+20 \\ 0.135x=432 \\ x=\frac{432}{0.135} \\ x=3,200 \end{gathered}$

The cost of the desktop is $3,200.

$x-400=3,200-400=2,800$

The cost of the laptop is $2,800.