intermediate algebra
posted by jackie on .
need the equation for this problem. Mike invested $706 for one year. He invested part of it at 5% and the rest at 3% at the end of the year he earned $28.00 in interest. How much did mike invest at each rate of interest

This problem requires writing and solving two "simultaneous" equations in two unknowns.
Let the two amounts invested by x (at 5%) and y (at 3%). Assume simple interest at that annual rate.
0.05 x + 0.03 y = 28.0
x + y = 706.
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Now solve those two equations.
0.05x + 0.05y = 35.30
0.02 y = 7.30
y = $365.00
x = 706  365 = $341.00