SOLUTION: 1.)A drain can empty a swimming pool in 21 days. A second drain can empty this pool in 7 days. In how much time will the two drains working together empty the pool. ___days __

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Question 365375: 1.)A drain can empty a swimming pool in 21 days. A second drain can empty this pool in 7 days. In how much time will the two drains working together empty the pool. ___days ___hours?
I got stuck and didnt know what to do after I got 21/4
2.)Three times a number is subtracted from five times its reciprocal. The result is 14. Find the number?
Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website!
1.)A drain can empty a swimming pool in 21 days. A second drain can empty this pool in 7 days. In how much time will the two drains working together empty the pool. ___days ___hours?
I got stuck and didnt know what to do after I got 21/4
It's 21/4 days. = 5.25 days
= 5 days 6 hours
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2.)Three times a number is subtracted from five times its reciprocal. The result is 14. Find the number?
5/x - 3x = 14
5 - 3x^2 = 14x
3x^2 + 14x - 5 = 0
(3x - 1)*(x + 5) = 0
x = -5, x = 1/3

SOLUTION: 1.)A drain can empty a swimming pool in 21 days. A second drain can empty this pool in 7 days. In how much time will the two drains working together empty the pool. ___days ___hour

SOLUTION: 1.)A drain can empty a swimming pool in 21 days. A second drain can empty this pool in 7 days. In how much time will the two drains working together empty the pool. _days _hour