1.My bath has two taps and a plug hole（出水孔）.The cold tap on

1.My bath has two taps and a plug hole（出水孔）.The cold tap on its own fills the bath in 12 minutes,the hot one in 5 minutes.The plug hole can drain（排干）the bath in 30 minutes with the taps off.How long will the bath take to fill if I leave both taps on with the plug out?
2.If the only sister of your mother's only brother has an only child,what would be your relationship to that child?