I can't figure out how to work out letters A and D. These are the answers I was provided to the questions, but I don't know how to work them out.

Assume that you have purchased a new home and arranged for a mortgage in the amount of $190,000.The loan is at 4.00 percent over 30 years. The monthly payment is $907.09.

A. How much of the loan's principal will you pay over the first 3 years of the loan?

$410,452

B. How much total interest will you pay over the last 10 years of the loan?

$19,257

C. What will be your loan balance after 15 years?

$122,631

D. What is the effective rate on your loan?

4.07%