Difference between CI and SI for 2 years is given: find the sum

The same question, asked 3 times: CDS 1 2017*, CDS 2 2017*, CDS 1 2021. Every wording below, oldest first.

Try each one first, then open its answer.

Question 1
CDS 1 2017
37 $The difference between the simple and the compound interest on a certain sum of money at 4% per annum in 2 years is Rs. 10. What is the sum ?$
Tap an option to check your answer.
Question 2
CDS 2 2017
43 $The difference between the compound interest (compounded annually) and simple interest on a sum of money deposited for 2 years at 5% per annum is Rs. 15. What is the sum of money deposited ?$
Tap an option to check your answer.
Question 3
CDS 1 2021
33 $The difference between the compound interest (compounded annually) and the simple interest on a certain sum of money at 12% per annum for 2 years is Rs. 72. What is the principal amount?$
Tap an option to check your answer.

Question 1