In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Q: Problem: two pipes can fill a tank in 18 minutes and 20 minutes . an outlet pipe can empty the tank in 45 minutes . if all the pipes are opened when the tank is empty , then how many minutes will it take to fill the tank ? 
Options: a ) 1 / 15 , b ) 1 / 16 , c ) 1 / 11 , d ) 1 / 10 , e ) 1 / 12

A: e
****
Q: Problem: a man can row upstream at 26 kmph and downstream at 30 kmph , and then find the speed of the man in still water ? 
Options: a ) 29 , b ) 28 , c ) 30 , d ) 32 , e ) 23

A: b
****
Q: Problem: to asphalt 1 km road , 30 men spent 12 days working 8 hours per day . how many days , 20 men will spend to asphalt a road of 2 km working 9 hours a day ? 
Options: a ) 34 , b ) 36 , c ) 32 , d ) 40 , e ) 44

A:
c
****