Some practice questions

1.  Arun can do a piece of work in 15 days .Sam can do it in 10 days how long will they take to work together?

            Ans. 
             15*10/15+10 = 6 days  [ short cut  ab/a+b ]



2.  P and Q can do a piece of work in 4 days. If P alone can complete the same in 12 days.In how many days can  Q alone complete it?

              Ans :   
                       4*12/8 =6 days  [ab/a-b]


3. 3 men can complete a work in 10 days.In how many days 10 men complete the same work?

              Ans:
                         3*10/10 = 3