Question 128975
.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