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 $1800 at 7% but i can't figue out how to get there.
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$\displaystyle \displaystyle (x)(.045)+(y)(.07)=144$ $\displaystyle \displaystyle x+y=2200$ How do you solve a system of linear equations now?
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
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