Let the original price of the sugar per kg be Rs. X. Let the quantity of sugar purchased initially be Y units in Rs. 270.
Thus, X × Y = 270 ….(1)
Given: Price of sugar decreased by 10%.
∴New price of sugar per Kg $( = \;X - \frac{{10}}{{100}}X)$
= 0.9X
Since the man could buy 1 more kg on his reduction of price, hence
⇒ Quantity of sugar purchased = Y + 1
As the total expenditure remains the same i.e. Rs. 270, therefore
⇒ 0.9X × (Y + 1) = 270 …(2)
Dividing equation (1) by (2), we get
$( \Rightarrow \frac{Y}{{0.9 \times \left( {Y + 1} \right)}} = 1)$
⇒ Y = 0.9Y + 0.9
⇒ Y = 9 units
∴ From equation (1) we get, X = Rs. 30