x + y + z = 50
x + y = 38
x = 38 - y
z = 12
0.05x + 0.10y + 0.25 (12) = 5.20
0.05x + 0.10y + 3.00 = 5.20
0.05x + 0.10y = 2.20
0.05 (38 - y) + 0.10y = 2.20
1.90 - 0.05y + 0.10y = 2.20
0.05y = 0.30
y = 6
0.05x + 0.10 (6) = 2.20
0.05x = 1.60
x = 32
32 nickles
6 dimes
12 quarters