First of all, the first problem is to use the average capital method to repay (the repayment amount is the largest in the first month, and then decreases year by year).

1, annual repayment formula:

Annual repayment amount = principal /n+ [principal-principal/n * (t-1)] * annual interest rate.

Where n represents the loan period and t represents the repayment period.

Substituting the data into the formula, the repayment amount in the first year is:

800/10+[800-800/10 * (1-kloc-0/)] *10% =1.6 million yuan;

The repayment amount in the second year is:

800/10+[800-800/10 * (2-1)] *10% =15200 yuan;

And so on.

2. Total interest = principal * annual interest rate * (loan period /2+0.5)

800 *10% * (10/2+0.5) = 4.4 million yuan.

3. The total repayment in10 year is 800+440 =12.4 million yuan.

Secondly, the second question is simple. Total interest: 800 * 10% */kloc-0 = 8 million yuan (interest is not repaid every year, 800,000 yuan), and the total repayment amount in10 years is 800+800 =160,000 yuan.