We know that price of petrol is directly proportional to its volume i.e., as volume of petrol increases, its price also increases proportionately.
In direct proportion, ratio of two proportional quantities is always constant.
Given price of 1 litre petrol is ₹78.
For 2.2 litre of petrol, price will be
x2.2=781
⟹ x = ₹171.6
∴ Price of 2.2 litre petrol = ₹171.60
For price ₹130, volume of petrol will be
130x=781
⟹ x = 1.67 litre
∴ For ₹130, we get 1.67 litre of petrol.
For price ₹101.4, volume of petrol will be
101.4x=781
⟹ x = 1.3 litre
∴ For ₹101.4, we get 1.3 litre of petrol .
For 3.9 litre of petrol, price will be
x3.9 = 781
⟹ x = ₹304.20
∴ Price of 3.9 litre of petrol = ₹304.20