Solve for X can you explain how to do this problem I'm not sure where to start. would really Appreciate it​

Brady has a 20 year fixed rate mortgage for $215,500 with monthly payments of 1,305.89.the annual interest rate is 4%. what is the total cost of the principal and interest for this loan rounded to the nearest dollar

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?

If f(x) = 2x + 8 and g(x) = x4, what is (gº)?