$A$ tap can fill the 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?

$A$ cistern has a leak which would empty it in $8$ $hours$. $A$ tap is turned on which admits $6$ $litres$ a $minute$ into the cistern,and it is now emptied in $12$ $hours$. The cistern can hold (in $litres$):

Two pipes $A$ and $B$ can fill a tank in $24$ $min.$ and $48$ $min.$ respectively. If both the pipes are opened simultaneously,after how much time (in $minutes$) $B$ should be closed so that the tank is full in $20$ $minutes$?

$A$ water tank is two-fifth full. Pipe $A$ can fill a tank in $10$ minutes,and pipe $B$ can empty it in $6$ minutes. If both the pipes are opened,how long will it take to empty or fill the tank completely?

$A$ water tank has two pipes. The empty tank is filled in $12$ $min$ by the $1$st pipe and the full tank is emptied by the $2$nd pipe in $20$ $min$. What is the time required to fill the $1/2$ full tank when both pipes are in action (in $min$)?

$A$ tank can be filled by one tap in $20$ $min$ and by another tap in $60$ $min$. Both the taps are kept open for $5$ $min$ and then the $1$st tap is shut off. After this,how much more time (in $min$) will it take for the tank to be completely filled?