6I need some help with this one please.

A chemical substance has a decay rate of 7.5% per day. The rate of change of an amount N of the chemical after t days is given by = -0.075N 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 t=0. How much will remain after 6 days? c) What is the rate of change of the amount of the substance after 6 days? d) After how many days will half of the original 800 g of the substance remain? a) N(t) = b) After 6 days, g will remain. (Round to the nearest whole number as needed.) c) After 6 days, the rate of change is g/day (Round to one decimal place as needed.) d) Half of the substance will remain after days. (Round to one decimal place as needed.)