The decay of 277 mg of an isotope is described by the function a(t)= 277e-0.019t, where t is time in years. find the amount left after 64 years. round your answer to the nearest mg.

The decay of 277 mg of an isotope is described by the function
A(t)= 277e-0.019t,
where t is time in years.
To find the amount left after 64 years,

We substitute t = 64 in the expression.
A(t=64)= 277e-0.019(64)
or A(t=64) = 277 * e-1.216
                 = 277 * 0.29
                 = 82 mg