Alex is currently working full time and plans to retire in 20 years from now. He believes he will need $3,500 per month for an expected retirement period of 30 years. As of now he has saved $200,000 in a retirement account. He wants to be well prepared for the retirement and wants to save as much as he needs per month as he is working. How much does Alex need to save every month if the rate of return he can obtain is 6%?