Price rises by r%: by what percent must consumption fall to keep expenditure the same

The same question, asked 2 times: CDS 2 2017*, CDS 1 2018. Every wording below, oldest first.

Try each one first, then open its answer.

Question 1
CDS 2 2017
44 $When prices rise by 12%, if the expenditure is to be the same, what is the percentage of consumption to be reduced ?$
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Question 2
CDS 1 2018
21 $If the price of wheat rises by 25%, then by how much percent must a man reduce his consumption in order to keep his budget the same as before?$
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