Question 677746
Let x=number of days needed to empty the pool with both drains working together
Then both drains working together can empty at the rate of 1/x pool per day
First drain empties at the rate of 1/16 pool per day
Second drain empties at the rate of 1/8 pool per day

Sooooo
1/16+1/8=1/x  multiply each term by 16x
x+2x=16
3x=16
x=5 1/3 days---time required to empty pool when both drains are working together

CK
In 5 1/3 or 16/3 days drain 1 empties (16/3)(1/16)=1/3 of the pool
In 16/3 days second drain empties (16/3)(1/8)=2/3 of the pool
Together in 16/3 days they empty 1/3 +2/3 =3/3 (and that's one pool:))

Hope this helps---ptaylor