How would you solve this problem??

A piggy bank contains only nickels and dimes. In all there are 42 coins with a total value of $3.85. How many nickels are in the piggy bank??

3 answers

two equations
: n+d=42
.05n+.10d=3.85 or 5n+10d=385
Sorry forgot to post the answers, which one would it be??
And can you show how you solved it??

A-3
B-7
C-17
D-35

Thanks
Ok I got it. Its process of elimination. So it would be B-7.