# Math Help - Word Problem

1. ## Word Problem

The Computer Club invested $2200, part at 4.5% interest and the rest at 7%. The total annual interest earned was$144. How much was invested at each rate?

The answser is $400 at 4.5% and$1800 at 7% but i can't figue out how to get there.

2. $\displaystyle (x)(.045)+(y)(.07)=144$

$\displaystyle x+y=2200$

How do you solve a system of linear equations now?

3. Actually I figured it out. Instead of using 2 variables I did Amount @ 4.5% = x, so then the amount at 7% = 2200-x

so it goes:
.045x + .07(2200-x)=144

then I sloved for x and got 400. So it is \$400@ 4.5% and if the amount @ 7% is 2200-x it would = 1800