A can do a piece of work in 30 days, while B alone can do it in 40 days. In how many days can A and B working together do it?
A17 and 1/7
B27 and 1/7
C42 and 3/4
D70
A17 and 1/7
B27 and 1/7
C42 and 3/4
D70
Related Questions:
A can do th of a work in 4 days and B can do th of the same work in 5 days. In how many days they can finish the work, if they work together?