A cistern can be filled by a tap in 4 hours while it can be emptied by another tap in 9 hours. If both the taps are opened simultaneously, then after how much time will the cistern get filled?
On his way home from shopping. Mobarok must travel due south for 5 miles and then due east for another 12 miles to reach his house. If Mobarok could travel in a straight line from the store to his house, how many fewer miles would he travel?