Please I need help with this 6-41 And 6-53 Please I need step by step solution and clear writing

Book used Engineering Economic Analysis (12th Edition)

Bill Anderson buys a car every 2 years as follows: initially he makes a down payment of $12,000 on a $30,000 car. The balance is paid in 24 equal monthly payments with annual interest at 12%. When he has made the last payment on the loan, he trades in the 2-year-old car for $12,000 on a new $30,000 car, and the cycle begins over again. 6-41 Doug Jones decided on a different purchase plan. He thought he would be better off if he paid $30,000 cash for a new car. Then he would make a monthly deposit in a savings account so that, at the end of 2 years, he would have $18,000 in the account. The $18,000 plus the $12,000 trade-in value of the car will allow Doug to replace his 2-year-old car by aying $30,000 for a new one. The bank pays 3% interest, compounded monthly. (a) What is Bill's monthly loan payment? (b) What is Doug's monthly savings account deposit? (c) Why is Doug's monthly savings account deposit smaller than Bill's payment