The total interest for one year is:

3,000,000× 5,000,000 ‰×12 =180,000.00 (yuan)

The monthly interest is: 15000.00 yuan.

If the principal and interest are repaid in equal amount every month, the monthly interest rate is 0.5%.

Monthly repayment of 3 million yuan 1 year (12 months):

3000000 * 0.5% * (1+0.5%)12/[(1+0.5%)1] = 2581.

Total interest: 258199.29 *12-3000000 =167253.6.