Pipes $P$ and $Q$ can fill a tank in $10$ and $12$ $h$, respectively, and pipe $C$ can empty it in $6$ $h$. If all the three are opened at $7$ $am$, at what time will one-fourth of the tank be filled?

$A$ tap can fill a tank in $25$ $minutes$ and another can empty it in $50$ $minutes$. Find out whether the tank will be filled up or emptied and in how many $minutes$?

Two pipes $A$ and $B$ can fill a tank in $30$ $minutes$ and $45$ $minutes$ respectively. Pipe $C$ can empty the tank in $36$ $minutes$. Initially,pipes $A$ and $B$ are opened. After $12$ $minutes$,pipe $C$ is also opened. What is the total time (in $minutes$) required to fill the tank?

$A$ water tank is $\frac{2}{3}$ full. Pipe $A$ can fill the tank in $10$ $minutes$ and pipe $B$ can empty it in $6$ $minutes$. If both the pipes are open,how long will it take to empty the tank completely?

One fill pipe $A$ is $3$ times faster than second fill pipe $B$ and takes $32$ minutes less than the fill pipe $B$. When will the cistern be full if both the pipes are opened together?

Two pipes can fill a tank in $20$ and $24$ $minutes$ respectively and a waste pipe can empty $3$ $gallons$ per $minute$. All the three pipes working together can fill the tank in $15$ $minutes$. The capacity of the tank is?