Successive yearly percent changes (salary, sales, population): present value, original value or a missing rate

This type of question, asked 3 times: 8 Aug 2022 Tier II, 18 Jan 2025 Tier II, 20 Jan 2025 Tier II. All 4 questions below, oldest first.

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Question 1
8 Aug 2022 Tier II
97 $Three years ago, Raman's salary was ₹45000. His salary is increased by 10 percent, A percent and 20 percent in first, second and third year respectively. Raman's present salary is ₹83160. What is the value of A?$
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Question 2
18 Jan 2025 Tier II
9 $The population of a place increased to 50,000 from 2016 to 2018 at the rate of 6% per annum, and continued the same trend for the next 3 years. If A is the population in 2016 and B is the population in 2020, both are approximated to the next possible integers, then the value of B - A is:$
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Question 3
20 Jan 2025 Tier II
8 $Two years ago, the population of a town was 9487500. Due to migration to big cities, it decreases every year at the rate of 8%. The present population of the town is:$
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Question 4
20 Jan 2025 Tier II
22 $Amit gets 6% increase in his sale amount in the first year and 20% in the second year, with that his present sale is ₹254400, what was his sale (in ₹) two years ago?$
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Question 1