I need help answering these two questions.

1. Find the monthly payments on a $250,000, 20 year mortgage with monthly payments at a nominal 12% rate. 2. If you take out a $300,000 mortgage at a nominal 7% yearly interest rate, what kind of down payment would you need to make in order for your monthly payments to be $2000 for 20 years? What percent of the house does that down payment represent