Answer:
15 nickels and 8 dimes
Explanation:
Let N = number of nickels and D = number of dimes
N - D = 7 (the number of nickels exceeds the number of dimes by 7.)
or
N = D + 7
Total value of N nickels = 5N
Total value of D nickels = 10D
Combined total value => 5N + 10D = 155
Substitute for N in terms of D
==> 5(D + 7) + 10D = 155
5D + 35 + 10D = 155
15D + 35 = 155
15D = 155 - 35
15D = 120
D = 120/15
D = 8
N = D + 7 = 8 + 7 = 15
15 nickels and 8 dimes