The price of the sugar rise by 25%. If a family wants to keep their expenses on sugar the same as earlier, the family will have to decrease its consumption of sugar by

Let the initial expenses on Sugar was Rs. 100.
Now, Price of Sugar rises 25%. So, to buy same amount of Sugar, they need to expense,
= (100 + 25% of 100) = Rs. 125.
But, They want to keep expenses on Sugar, so they have to cut Rs. 25 in the expenses to keep it to Rs. 100.
Now, % decrease in Consumption,
$$\frac{{25}}{{125}} \times 100 = 20\% $$

Mind Calculation Method;
100 === 25%↑ ===> → 125 === X%↓ ===> 100
Here, X = $$\frac{{25}}{{125}} \times 100 = 20\% $$