Two pipes $A$ and $B$ can fill a tank in $15$ hours and $20$ hours respectively,while a third pipe $C$ can empty the full tank in $25$ hours. All three pipes are opened in the beginning. After $10$ hours,pipe $C$ is closed. Find the total time (in hours) in which the tank will be full.

$A$ cistern has three pipes $A, B$ and $C$. Pipes $A$ and $B$ can fill it in $3 \, h$ and $4 \, h$, respectively, while pipe $C$ can empty the completely filled cistern in $1 \, h$. If pipes are opened in order at $3:00 \, pm$, $4:00 \, pm$ and $5:00 \, pm$, respectively, at what time will the cistern be empty?

Three pipes $A, B$ and $C$ can fill a tank in $6$ $hours$. After running them together for $2$ $hours$, the tap $C$ is closed and $A$ and $B$ fill the remaining part in $7$ $hours$. How much time (in $hours$) would $C$ take to fill the tank alone?

$A$ water tank has two taps $A$ and $B$. Tap $A$ can fill it in $6$ hours,and tap $B$ can empty it in $5$ hours. If both taps are opened simultaneously,how much time (in hours) is required to empty the tank?

Two pipes $A$ and $B$ can fill a cistern in $15$ and $20$ $min$,respectively. Both the pipes are opened together,but after $2$ $min$,pipe $A$ is turned off. What is the total time (in $minutes$) required to fill the tank?

$A$ tap can fill a cistern in $8$ $hours$ and another can empty it in $16$ $hours$. If both the taps are opened simultaneously,the time (in $hours$) to fill the tank is?