Jill is 20 years old. She has two goals in life. First, she wants to buy a new BMW for $75,000 at the age of 30. Second, she wants to retire at the age of 65 with a monthly income of $6,000. Jill will save $500 per month for the next 10 years. Jill expects to live to 90. If Jill can earn 7% per annum both before and after she retires, how much must Jill save every month from the age of 30 to 65, so that she can retire with the monthly income she desires