Machine A can produce 100 units in 5 hours. Machine B can produce 100 units in 8 hours. If they work together, approximately how many units can they produce in 4 hours?

✓ Correct Answer: Option B

Machine A's rate is 100/5 = 20 units/hour. Machine B's rate is 100/8 = 12.5 units/hour. Their combined rate is 20 + 12.5 = 32.5 units/hour. In 4 hours, they produce 32.5 * 4 = 130 units.