A and B can do a work in 20 and 30 days, respectiveyl .They completed the work in 10 days with the help of C. In how days can C alone do the work?

A and B can do a work in 30 days and 10 days respectively. If they work on alternate days beginning with A, in how many days will the work be completed?

A and B can do a work in 30 days and 10 days respectively. If they work on alternate days beginning with A, in how many days will the work be completed?

A alone can do a work in 15 days. A is 20% less efficient than B. In how many days can B alone do the work?