# Pipe & Cisterns

**Fast trick to solve the pipe and cisterns.**

##### If two pipe '**A**' and '**B**' operate both at the same time that can fill a tank in **3 hr**. A water pipe '**A**' fill the tank '**5 hr**' faster than the pipe '**B**' how many hr does it take the pipe '**A**' to fill the tank.

### STEP 1 :

#####
Let the tank can be filled by pipe '**A**' in **x hr**

than pipe '**B**' in '**x + 5 hr**'

so in 1hr tank filled by **A** = **1/x**

and in 1hr tank filled by **B** = **1/(x + 5)**

### STEP 2 :