Price of sugar is increased by 25% in order to increase the expenditure a lady must reduce her commissions by ?

It Can be done using a simple formula for percentage :
Decrease in consumption = [% Price increase / (100 + % Price Increase) ] × 100
So , If price of onion rises by 25% =>
Decrease in consumption = [ 25 / (100 + 25) ] × 100
= [ 25 / 125 ] × 100 = 20