A radioactive Isotope decays at a rate proportional to the amount present. If the Isotope has a decay rate of 12.10% per thounsands of years and the current amount of the isotope is 135.2 mg. How much of the isotope will remain after 2.2 thounsand years? Round your answer to the nearest tenth. Write the value of each variable. If the value is unknown write a ? (write only the numerical value no units) 1) y= 2) a = 3) r= 4) t=