SOLUTION: A man invested a sum of money at 6%. A second sum $400 more than the first sum is invested at 3%. A third sum 4 times as much as the first sum is invested at 4%. The total annual

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Question 128975: A man invested a sum of money at 6%. A second sum $400 more than the first sum is invested at 3%. A third sum 4 times as much as the first sum is invested at 4%. The total annual incomr is $237, How much has he invested at each rate?
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
.06X+.03(X+400)+.04(4X)=237
.06X+.03X+12+.16X=237
.25X+12=237
.25X=237-12
.25X=225
X=225/.25
X=900 INVESTED @ 6%.
900+400=1300 INVESTED @ 3%
900*4=3600 INVESTED @ 4%.
PROOF
.06*900+.03*1300+.04*3600=237
54+39+144=237
237=237