When 6 Bottles of Oil were Taken out from This Tin :

A tin of oil was 4/5 full. When 6 bottles of oil were taken out from this tin and 4 bottles of oil were poured into it, it was 3/4 full. Oil of how many bottles can the tin contain? (All bottles are of equal volume)

1. 35
2. 40
3. 45
4. 50