'A' and ' B ' can do a work in 20 and 30 days respectively. They began the work together, but 'A left after some time and ' B ' finished the remaining work in 5 days. Then what is the number of days a
A). 8 days
B). 10 days
C). 12 days
D). 14 days
10 days
B alone worked for 5 days
work done by B in 5 days = 5/30 = 1/6
A + B together finished 1 - 1/6 = 5/6 work.
A + B do I work in 20x30/20x30 = 600/50 = 12 days
A + B do 5/6 work in 12 x 5/6 = 10 days.