Percentage Constancy Example.

Question
A reduction of 10% in the price of sugar enables a housewife to buy 6.2kg more for Rs279. Find reduced price per kilogram.
 (a) Rs 5
(b) Rs 4.5
(c) Rs 4.05
(d) None of these

Things to remember !!

Following are three things that needs to be constantly revised. they are Pythagoras Triplet, Ratio and Percentage equivalent and Percentage constancy.
I suggest you bookmark this post and revise them as much as possible.