SOLUTION: Jon invested $21,000, part at 18% and part at 8%. If the total interest at the end of the year is $1,980, how much did he invest at 18%.

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Question 84145: Jon invested $21,000, part at 18% and part at 8%. If the total interest at the end of the year is $1,980, how much did he invest at 18%.
Answer by checkley75(3666) About Me  (Show Source):
You can put this solution on YOUR website!
.18X+.08(21000-X)=1980
.18X+1680-.08X=1980
.1X=1980-1680
.1X=300
X=300/.1
X=3000 AMOUNT INVESTED @ 18%.
PROOF
.18*3000+.08(21000-3000)=1980
540+.08(18000)=1980
540+1440=1980
1980=1980