After decreases in petrol prices by 20%, a person is able to buy 3 litre more petrol for Rs. 540. Find the original and increased price of petrol per litre.
Sol: Let the original price(O.P.) be Rs. X per kg. New price(N.P.) = 80% of x = Rs. 4x/5per kg. Quantity of petrol the person could buy at original price = 540/xltr. Quantity of petrol he can buy at new price = ltr. =675/x-540/x 3 = 135/x= 3 ⇒ 3 = 135 ⇒ = 45 O.P. = Rs.45 and N.P. = Rs. 4x/5= 4*45/5= Rs.36
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