$A$ 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?

$A$ pipe can fill a tank in $10 \, h$, while another pipe can empty it in $6 \, h$. Find the time (in $hours$) taken to empty the tank when both the pipes are opened simultaneously.

$A$ water tank has three taps $A$,$B$ and $C$. Tap $A$,when opened,can fill the water tank alone in $4$ $hours$. Tap $B$,when opened,can fill the water tank alone in $6$ $hours$. Tap $C$,when opened,can empty the water tank alone in $3$ $hours$. If taps $A$,$B$ and $C$ are opened simultaneously,how long will it take to fill the tank completely? (in $hours$)

Three pipes $A$,$B$,and $C$ can fill a cistern in $10$,$12$,and $15$ $hours$,respectively,while working alone. If all the three pipes are opened together,the time taken to fill the cistern will be:

Two pipes,$A$ and $B,$ can separately fill a tank in $6$ $hours$ and $8$ $hours,$ respectively. Both the pipes are opened together,but $1 \frac{1}{2}$ $hours$ later pipe $A$ is turned off. How much time (in $hours$) will it take to fill the tank?

There are two taps $A$ and $B$ to fill up a water tank. The tank can be filled in $40$ $min,$ if both taps are on. The same tank can be filled in $60$ $min,$ if tap $A$ alone is on. How much time (in $minutes$) will tap $B$ alone take to fill up the same tank?