Karen has to make rental payments of $1000 at the start of every month, throughout the four-year duration of her university course. Her university fees are $4000 to be paid at the start of each year. She earns $1500 per month (paid at the end of each month) from a part time job. Assume an interest rate of 8% p.a. and that she keeps the part-time job for the next four years. How much money, in present value terms, can she withdraw each month for the next four years?