Suppose that = −0.0004332 A(t) represents a mathematical model for the radioactive decay...

Suppose that = −0.0004332 A(t) represents a mathematical model for the radioactive decay of radium-226, where A(t) is the amount of radium (measured in grams) remaining at time t (measured in years). How much of the radium sample remains at the time t when the sample is decaying at a rate of 0.002 gram per year?