Answer both a) and b) with fully typed solutions (all steps)Use strategies taught in grade 12 calculus class.Thanks!

A radioactive substance decays in such a way that the amount left after t years is given by the function A(t) = 100e-0.#t . The amount, A, is expressed as a percent. (5 marks) a) Find the function, A'(t) , that describes the rate of decay. b) What is the rate of decay when 40% of the substance is gone