E

Erfan

3

S

Sree

20% work in 3 days

So 100% work can be finished in 15 days.

80% of the work was completed by B in 20 days.

So he can do the 100% work in 25 days

```
A+B B
15d 25d
```

LCM 75

So the efficiency of A and B is 5

Efficiency of B alone is 3.

From that, efficiency of A is 2.

Now the total work ÷ A's efficiency = 75÷2=37.5

2