The radioactive substance uranium-240 has a half-life of 14 …

The radioactive substance uranium-240 has a half-life of 14 hours. The amount A (t) of a sample of uranium-240 remaining (in grams) after t hours is given by the following exponential function.A(t)=390012t14Round both answers to the nearest gram as necessary.a) Find the initial amount of the sample.b) Find the amount of the sample remaining after 20 hours.