Due to an increase in the price of sugar by 25%,by how much percent must a householder decrease the consumption of sugar so that there is no increase in the expenditure on sugar?

Answer 1

(1.25x)(r) = x
1.25r = 1
r = 1/1.25 = .8 = 80%

So it must be reduced by 20%

check:
suppose the original was $100
after the increase it would be 125
after a reduction of 20% is would be
.8(125) = 100