Question 585457

.05n+.10d=7
n+d=100
n=100-d
.05(100-d)+.10d=7
5-.05d+.10d=7
.05d=7-5
.05d=2
d=2/.05
d=40 number of dimes.
n+40=100
n=100-40
n=60 number of nickles.
PROOF:
.05*60+.10*40=7
3+4=7
7=7