- A20
- B49
- C21
- D18
Step-by-Step Solution
Combined rate = 1/28 + 1/70 = 5/140 + 2/140 = 7/140 = 1/20 per hour. Time = 20 hours.
Answer: A) 20
Two pipes can fill a swimming pool separately in 28 hours and 70 hours. Running together, how many hours do they take?
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