Let the price of petrol be ₹ 100 per litre. Let the user use 1 litre of petrol. Therefore, his expense on petrol = 100 × 1 = ₹ 100 Now, the price of petrol increases by 25% Therefore, the new price of petrol = ₹ 125. As he has to maintain his expenditure on petrol constant, he will be spending only ₹ 100 on petrol. Let ‘x’ be the number of litres of petrol he will use at the new price. Therefore, 125×x=100 ⇒x=
100
125
=
4
5
=0.8litre He has cut down his petrol consumption by 0·2 litre =