We can set up a system of equations.
x + y = 111
0.25x + 0.10y = 18.30
x + y = 111
Subtract 'y' to both sides:
x = -y + 111
Plug in '-y + 111' for 'x' in the 2nd equation:
0.25(-y + 111) + 0.10y = 18.30
Distribute 0.25 into the parenthesis:
-0.25y + 27.75 + 0.10y = 18.30
Combine like terms:
-0.15y + 27.75 = 18.30
Subtract 27.75 to both sides:
-0.15y = -9.45
Divide -0.15 to both sides:
y = 63
Plug this back into any of the two equations to find the 'x' value.
x + y = 111
x + 63 = 111
Subtract 63 to both sides:
x = 48
So there are 48 quarters and 63 dimes.
