PLEASE help (both parts) asap thank you!!

You want to buy a house at the end of 7 years. At that time you estimate that you will need $150,000 to make the downpayment on a house. a) Assuming you can save $15,000 per year for the next 7 years and invest it at 6%, will you achieve your goal? b) If you feel you can be more aggressive and can earn 8% instead of 6%, how much would you have to save per year to meet your $150,000 goal