Machine A can produce 100 widgets in 4 hours. Machine B can produce 100 widgets in 5 hours. If both machines work together, how many widgets can they produce in 3 hours?

✓ Correct Answer: Option C

Machine A's rate is 25 widgets/hour. Machine B's rate is 20 widgets/hour. Combined, they produce 45 widgets/hour. In 3 hours, they produce 45 * 3 = 135 widgets.