From the language of the question, it appears that there will be two payments of $5200.00 each in a year. Answer is being given on this basis.

Total payments in a year = $5200.00 * 2 = $10,400.00

Nominal interest rate:

($10,400.00 / Present value: $62,400.00) * 100 = 16.67% .

Present value: $62400.00

Periodic payment: $5200.00

Payment interval: 6 months

term: 25 years

conversion period: annually

Interest rate: ?

How to find the interest rate please show me the process how to get it.

thank you,

Julio.