A reduction of 25% in the price of sugar enables a person to buy 5 Kg…

Price × Consumption = Total Expenditure

(If expenditure is same then price and consumption is inversely proportional to each other)

Therefore,

             Original   :   Changed

Price  =       4       :         3                  [25% = \(\frac{1}{4}\)]

Cons.=       3       :          4

Diff. in consumption = 1R = 5kg (given)

Original consumption = 3R = 3 × 5 = 15kg

Hence, Original Price per Kg =  \(\frac{Total Price}{Total Quantity}\) = \(\frac{120}{15}\) = Rs 8/kg