A chemical substance has a decay rate of 6.5% per day. The rate of change of an amount N of the chemical after t days le dN given by dt = -0.065N. a) Let No represent the amount of the substance present at t = 0. Find the exponential function that models the decay. b) Suppose that 800 g of the substance is present at ta0. How much will remain after 3 days? c) What is the rate of change of the amount of the substance after 3 days? d) After how many days will half of the original 800 g of the substance remain? a) N(t) = b) After 3 days, g will remain. (Round to the nearest whole number as needed.) c) After 3 days, the rate of change is g/day. (Round to one decimal place as needed.) ) Half of the substance will remain after days. (Round to one decimal place as needed.)