question_answer

Two pipes A and B can separately fill in a cistern 15 and 10 minutes respectively and a waste pipe can discharge 7 litres per minute. If all the pipes are opened when the cistern is full, it in emptied in 2 min. How many litres does the cistern hold?                                  

A)  21 ltr

B) 30 ltr

C) 40 ltr

D) 35 Itr

E) 45 Itr