Answer:
She bought 10 $0.02 stamps and 30 $0.41 stamps.
Step-by-step explanation:
If she bought x $0.02 stamps then she bought 3x $0.41 stamps.
So we have the equation:
0.02x + 0.41 * 3x = 12.50
0.02x + 1.23x = 12.50
1.25x = 12.50
x = 10.
So she bought 10 $0.02 stamps and 30 $0.41 stamps.