The page contains multiple math problems, mainly focusing on population growth and depreciation. Here's the summary of relevant questions:

1. Population growth rate problems:

   • 8A: The population was 10,000 last year and increased to 10,210. Find the growth rate.
   • 8B: The population decreased from 10,000 to 9,780. Find the decrease rate.
   • 8C: Population increased from 1,000 to 1,020. Find the growth rate.
   • 8D: A town's population increased by one-fifth in a year. Find the growth rate.

2. Population changes due to migration:

   • 9A: The population of a village is 12,000. Due to birth (+1,000) and immigration (+2,000), find the new population.
   • 9B: Starting population of 7,200, where 500 people migrated in and 200 died. Find the population after a year.

3. Depreciation problems:

   • Questions involve calculating the depreciation of various items like telephones, machinery, and motorbikes using different rates over time.

Would you like me to solve a specific problem from these? Let me know the question number! Here are five follow-up questions you can consider:

1. How do you calculate population growth rates using percentages?
2. What formula is used to calculate depreciation with a fixed rate?
3. How do you handle population changes due to births, deaths, or migration?
4. Can you explain the "one-fifth" growth rate in Question 8D?
5. How do you calculate the final value after multiple years of depreciation?

Tip: For percentage-based problems, always start by using the formula:
$\text{Growth/Decrease Rate} = \frac{\text{Change in Population}}{\text{Initial Population}} \times 100$