There are two rectangular swimming pools with the same base and height. When they are full, the water in swimming pool $A$ can be drained in $10$ minutes while the water in swimming pool $B$ can be drained in $6$ minutes. If both of two swimming pools start to drain water at the same time, after how many minutes the height of $A$\textquotesingle s waterline will be $3$ times that of $B$? 
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