Question

pipe A can fill a tank in 15 hrs. Find the time taken by pipe B to fill the tank if both A and B take 6 hrs to fill the tank completely

Answer 1

time taken by B=
$\frac{1}{6} - \frac{1}{15} = \frac{5 - 2}{30} = \frac{3}{30} = \frac{1}{10}$
10 hrs