I need a detailed explanation of solving this problem: You have purchased a new warehouse. To finance the purchase, you obtained a 25-year mortgage for 75% of $3,000,000 purchase price. The monthly...

I need a detailed explanation of solving this problem:

You have purchased a new warehouse. To finance the purchase, you obtained a 25-year mortgage for 75% of $3,000,000 purchase price. The monthly payment will be $17,100.

a) What is the APR?