Question 144857
Q+D=12 OR Q=12-D
.25Q+.10D=1.80
.25(12-D)+.10D=1.80
3-.25D+.10D=1.80
-.15D=1.80-3
-.15D=-1.20
D=-1.20/-.15
D=8 IS THE NUMBER OF DIMES.
Q+8=12
Q=12-8
Q=4 IS THE NUMBER OF QUARTERS.
PROOF
.25*4+.10*8=1.80
1+.80=1.80
1.80=1.80