<PRE><B>Question 753852</B>
pipe A can fill a tank in 5 hours more than pipe B. If both pipes are used simultaneously, it will take 6 hours to fill that same tank.. How long will it take for pipe A alone to fill that tank, and how long will it take for pipe B alone? 
time * rate = amount done
.
Let x = hours it takes pipe B alone
then
x+5 = hours it takes pipe A alone
.
6(1/x + 1/(x+5))= 1
multiplying both sides by (x)(x+5):
6((x+5) + x)= (x)(x+5)
6(2x+5)= x^2+5x
12x+30 = x^2+5x
30 = x^2-7x
0 = x^2-7x-30
0 = (x+3)(x-10)
x = {-3, 10}
throw out the negative solution (extraneous) leaving:
x = 10 hours (time it takes pipe B alone)
.
Pipe A alone:
x+5 = 10+5 = 15 hours</PRE>