An initial sample of 483 grams was found in a radioactive substance. The equation, A = 48360'038'5, gives the amount left in the substance after t years. a. How many grams of the substance will remain after 43 years? (Round your answer to one decimal place.) b. What is the half-life of the substance, that is, how long will it take for the substance to decrease to half its initial amount? (Round your answer to one decimal place.)