Question 121785
N+D=50 OR N=50-D
.05N+.10D=4.15
NOW REPLACE N WITH(50-D) & SOLVE FOR D
.05(50-D)+.10D=4.15
2.50-.05D+.10D=4.15
.05D=4.15-2.50
.05D=1.65
D=1.65/.05
D=33 IS THE NUMBER OF DIMES.
50-33=17 IS THE NUMBER OF NICKLES.
PROOF
.10*33+.05*17=4.15
3.30+85=4.15
4.15=4.15