A tank can be filled by a tap in 20 minutes and by another tap in 60 minutes . Both the taps are kept open for 10 minutes and then the first tap is shut off. After this, the tank will be completely filled in what time?

Combined Bank (সমন্বিত ব্যাংক) Sonali Bank Ltd Officer (Cash) 27.04.2018 গণিত নল ও চৌবাচ্চা (Pipes and cistern) 2018