The image you have uploaded contains a series of math problems related to interest rates and annuities. Let's go through the questions one by one:

1. Bu Yani's Simple Interest Problem

Bu Yani deposited Rp 20,000,000 in Bank A, and after 6 months, the amount became Rp 21,200,000. The problem asks for the interest rate provided by the bank.

This is a simple interest problem where we use the formula:

$A = P(1 + rt)$ Where:

• $A$ is the total amount (Rp 21,200,000),
• $P$ is the principal amount (Rp 20,000,000),
• $r$ is the annual interest rate (in decimal form),
• $t$ is the time in years (0.5 years, since 6 months is half a year).

2. Eka's Compound Interest Problem

In 2011, Eka saved Rp 10,000,000 with compound interest. By 2020, the amount became Rp 80,000,000. We need to find the amount in 2017.

The formula for compound interest is:

$A = P(1 + r)^t$ Where:

• $A$ is the amount (known in 2020, i.e., Rp 80,000,000),
• $P$ is the principal amount (Rp 10,000,000),
• $r$ is the annual interest rate (unknown),
• $t$ is the time in years.

We first calculate the interest rate from 2011 to 2020 and then use that rate to find the amount in 2017.

3. Imam and Rian's Compound Interest Problem

Imam and Rian both invest with compound interest. After 12 years, Imam has Rp 8,000,000 more than Rian. The difference between their amounts after 24 years is Rp 14,000,000. We need to find how much they each had at the start.

This involves comparing two compound interest scenarios with different time periods.

4. Loan Repayment with Compound Interest

A loan with a compound interest rate of 13% per year is to be repaid annually through annuities. The second installment is Rp 734,500, and we are asked to calculate the fourth installment.

This requires using the annuity formula for loan repayment:

$A = \frac{P \times r}{1 - (1 + r)^{-n}}$ Where:

• $A$ is the annuity (installment amount),
• $P$ is the loan amount,
• $r$ is the annual interest rate,
• $n$ is the total number of payments.

5. Monthly Annuity Problem

A merchant takes a loan of Rp 10,000,000 with monthly annuities. The interest rate is 6% per year, and the repayment period is 1 year. The questions are:

• What is the monthly annuity?
• What is the amount of the 5th installment?
• What is the remaining debt after the 7th month?

This requires applying the monthly annuity formula and calculating remaining debt after specific periods.

Let me know if you'd like me to solve a specific problem or provide more details! Here are five related questions you might find helpful:

1. What are the differences between simple and compound interest?
2. How do you calculate the total repayment amount in an annuity?
3. What happens to the interest rate calculation if the time is measured in months instead of years?
4. How can you use compound interest to determine the future value of an investment?
5. What are the benefits and drawbacks of using annuities for loan repayment?

Tip: Always ensure that time units (months, years) are consistent when working with interest formulas!