The ratio of oil and kerosene in the container is 3:2. When 30 litres of mixture is taken out and replaced by kerosene, the ratio becomes 3: 5. The total quantity of the mixture in the container is:

80 L

Let the quantity of oil = 3x,

                    kerosne = 2x

                         Total = 5x

If 30l of mixture is taken out, it contains 

30 x \(\frac{3}{5}\) = 18l of oil and 

30 x \(\frac{2}{5}\)  = 12l of kerosene

The new ratio, 

\(\frac{3x - 18}{2x - 12 + 30}\) = \(\frac{3}{5}\)

 \(\frac{3x - 18}{2x + 18}\) =  \(\frac{3}{5}\)

15x - (18 x 5) = 6x + (18 x 3)

              9 x   = 18 x 8

                 x   = 16

Total quanity of the mixture = 5x = 5 x 16 = 80L