Please help me understand how to solve these questions. I have the solutions but need to understand the calculations.

An adjustable rate mortgage loan with a teaser start rate of 1.0% for the first year, an index of the 11th District COFI rate, a margin of 2.0%, and periodic and lifetime interest rate increase caps of 1%/6% with semi-annual adjustments, would have a maximum interest rate of what for the first half of the fourth loan year if the 11th District COFI rate is 6.0% at that time?

a) 5.0% b) 6.0% c) 7.0% d) 8.0%

If the loan to value ratio is 75%, the stated annual interest rate is 5%, the loan term is 30 years fully amortized, and the down payment is $600,000, what is the purchase price of the property?

a) $600,000 b) $900,000 c) $1,800,000 d) $2,400,000

10) If the loan to value ratio is 75%, the stated annual interest rate is 5%, the loan term is 30 years fully amortized, and the down payment is $600,000, what is the monthly payment on the loan?

a) $3,220.93 b) $4,831.39 c) $9,662.79 d) $12,883.72

11) What is the APR on a 30-year fully amortizing fixed rate mortgage loan in the amount of $1,000,000 if the stated annual interest rate is 3.75% and the lender charges 2 points as an origination fee, $1,800 for an appraisal and $36 for a credit report? a) 3.93% b) 3.90% c) 3.75% d) 3.57% 12) If a lender wants to achieve an APR of approximately 4.50% on a 30-year fixed rate loan for $750,000 with a stated annual interest rate of 4.25 %, how many points should the lender charge the borrower?

a) 1 b) 2 c) 3 d) 4