Hello there! I can help you! This question represents exponential decay. The formula for exponential decay is A(1 - r)^t, were A = initial amount, r = rate )in decimal form), and t = time. In this case, we are talking about 2% decaying each month. 2% is 0.02 in decimal form. Subtract this number from 1. 1 - 0.02 is 0.98. That means each time, 98% of he money still remains. Now, we will raise that number to the 6th power, because 2% is per month, and we are solving for a period over 6 months. 0.98^6 is 0.88584238086. This is a long number, but DO NOT delete the number from your calculator. Now, multiply that number by 800 to find the amount after 6 months. When you do, you get 708.673904691 or 708.67 when rounded to the nearest hundredth. There. Lily's pan drive will be $708.67 after 6 months.
Note: I used the formula above to answer the question, because I would be able to give the answer easily.