Let the price paid per trip by a passenger be ηx. and auto rickshaw consumes y L petrol. Total expenditure in a trip =30×y=₹30y Total earning in a trip =3×x= ₹ 3x According to the question, 3x−30y=20%‌ of ‌30y ⇒‌‌3x−30y=‌
20×30
100
y⇒3x−30y=6y ⇒‌‌3x=36y‌‌∴x=12y Now, the price of petrol are reduced to ₹ 24 and passenger taken by auto-rickshaw are four. ∴ Total expenditure in a trip =24×y= ₹24y Total earning in a trip =4×x=₹4x Profit per cent ‌‌=‌