Aaron A. answered • 05/07/17

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We know that the interest at 7% is equal to .07(x) where x is the amount invested at 7%. The interest earned at 5% is equal to .05(2x+97). We know these 2 quantities combined is equal to 315.61, so we can formulate the equation

.07x+.05(2x+97)=315.61

.07x+.1x+4.85=315.61

.17x+4.85=315.61

.17x=310.76

x=1828

so he invests 1828$ at 7% and

he invests 2(1828)+97 = 3753$ at 5%

we can check this with .07(1828)+.05(3753) = 315.61