A Radioactive Substance Decays in Such a Way That the Amount

Short Answer

A radioactive substance decays in such a way that the amount of mass remaining after t days is given by the function $m ( t ) = 13 e ^ { - 0.015 t }$ where $m ( t )$ is measured in kilograms. Round your answers to three decimal places.
a) Find the mass at time $t = 0$ .
b) How much of the mass remains after 100 days?