Chelsea had 23 nickels and dimes worth $1.60

Answer 1

5 n + 10 d = 160
n + d = 23
so
d = (23-n)
5 n + 10 ( 23 - n) = 160
5 n - 10 n = 160 - 230
- 5 n = -70
n = 14
d = 9