Answer:Given
a can do a piece of work = 40 days
so, A's 1 day work =1/4
so, A's 8 day's work =8/40=1/5
remaining work = 1- 1/5= 4/5
Now, B can do 4/5 piece of work in =16 days
So, B’s 1 day's work = (4/5) /16= 4/ 5x6=1/20
Therefore, (A+B)’s 1 day's work = 1/40+1/20 =
1+2/40=3/40
∴ Both (A+B) can do a piece of work in =
1/days (3/40) = 40/3 days
= 13 1/3 days