Question

A does 4/5 of a work in 20 days. he then calls in b and they together finish the remaining work in 3 days how long B alone would take to do the whole work

Answer 1

here is the answer for your question

A can do 4/5th works in 20 days.
so he can do the whole work in 20*(5/4) =25 days.
remaining work after done 4/5 by A is=1-(4/5)=1/5
(A+B) can do the 1/5th work in 3 days.
means the can do the whole work in (3*5)=15 days.
so,(A+B)'s 1 days work=1/15
B's 1 day's work {(1/15)-(1/25)}=2/75
so B can alone do the whole work in 75/2,means in 37 1/2 days


Thank you

Answer 2

A=20*5/4=25days
A will do the remaining work 1-4/5=1/5
therefore A+B=1/5 în 3days
A+B=3*5=15
A+B=1days work 1/15
B 1 day work 1/15-1/25=2/75
B=75/2=371/2