Colin invested $32,000, part at 8% and part at 12%. If the total interest at the end of the year is $3,160, how much did he invest at each rate?

X = amount invested at 0.08.

32000-X = amount invested at 0.12.

X(0.08) + (32000-x)(0.12) = 3160
Solve for x and 32000-x.
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