Answer: 24/7
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Step-by-step explanation:
Let's say the pool is 4800 gallons. I'm picking this number since 8*6 = 48 and I tacked a few zeros at the end to make the volume a bit more reasonable for a swimming pool. This might be on the low end of the spectrum. It turns out that the actual volume doesn't matter and you can pick whatever favorite number you want.
The pool being 4800 gallons means Anita's rate is 4800/8 = 600 gallons per hour if working alone.
If Chao works alone, then the rate is 4800/6 = 800 gallons per hour.
Their combined rate is 600+800 = 1400 gallons per hour. This assumes neither person slows the other down.
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x = amount of time they work together
1400x = number of gallons cleaned after x hours
1400x = 4800
x = 4800/1400
x = (24*200)/(7*200)
x = 24/7 is the final answer
x = 3.43
It takes about 3.43 hours to clean the pool if they worked together, and if they didn't slow each other down.