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

intermediate algebra 
drwls,
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