Hi,
Let x represent the time second tank would take alone.
then the time the first tank to fill alone would be(x+3)
***Two pipes can fill a tank in two hours. Per hour is the equalizer.
1/x + 1/(x+3) = 1/2hr
Mulitplying each term on both sides of the equation by 2x(x+3) so as all denominaotrs = 1
2(x+3) + 2x = x(x+3)
solving for x
2x + 6 + 2x = x^2 + 3x
x^2 -x -6 = 0
factoring
(x-3)(x+1)= 0
(x-3)=0 x = 3,
(x+1)= 0 x = -1 (cannot use)
3hr = time second tank would take alone, first tank 6hr alone
checking our answer
1/6 + 1/3 = 1/6 + 2/6 = 3/6 = 1/2