Cost price of n articles equals selling price of m articles: find profit percent

The same question, asked 2 times: CDS 1 2021*, CDS 1 2024. Every wording below, oldest first.

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Question 1
CDS 1 2021
36 $The cost price of 100 mangoes is equal to the selling price of 80 mangoes. What is the profit percentage?$
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Question 2
CDS 1 2024
43 $The cost price of y articles is equal to selling price of z articles. If y : z = 5 : 4, what is the profit percentage ?$
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