**Question: ** Polonium-210 is a radioactive element with a half life of 140days. Assume that 20 milligrams of the element are placed in a lead container and that y(t) is the number of milligrams present t days later

a) Find the formula for y(t)

b) How many milligrams will be present after 12 weeks?

c) How long will it take for 75% of the original sample to decay?