Answer:
Number of dimes Sandy has = (20 - x)
Explanation:
Let the number of nickels Sandy has = N
And the number of dimes she has = D
Total number of coins she has = 20
N + D = 20 ------(1)
If she has the number of nickels = x
Therefore, expression that represents the number of dimes she has will be
x + D = 20
D = (20 - x)
Number of dimes Sandy has = (20 - x)