Question

A can do a work in 15 days and b in 9 days. if they work on it together for 5 days, then what fraction of work is left

Answer 1

A can do the work in 15 days
B can do the work in 9 days

in 1 day A does =1/15 part
in 1 day B does = 1/9 part

together in 1 hr they does =(1/15+1/9) part
= (3+5/45) part
= (8/45) part
they worked for 5 days,
work done = (8/45×5)=8/9 part
work left = (1-8/9) = 1/9 part