Question 995340
n = number of nickels
d = number of dimes


5n + 10d = 70
d = n + 4


Substitute the second equation into the first.


5n + 10(n + 4) = 70
5n + 10n + 40 = 70
15n = 30
n = 2


There are 6 dimes and 2 nickels.