Answer:
23 dimes; 32 nickel
Explanation:
Let n = number of nickels.
Let d = number of dimes.
A nickel is worth $0.05; n nickels are worth 0.05n.
A dime is worth $0.10; d dimes are worth 0.1d.
Number of coins:
d + n = 55
Value of the coins:
0.1d + 0.05n = 3.9
Solve d + n = 55 for d:
d = 55 - n
Substitute 55 - n for d in second equation.
0.1(55 - n) + 0.05n = 3.9
5.5 - 0.1n + 0.05n = 3.9
-0.05n = -1.6
n = 32
Substitute 32 for n in d + n = 55 and solve for d.
d + 32 = 55
d = 23
Answer: 23 dimes; 32 nickel