The half-life of a substance is how long it takes for half of the substance to decay or become harmless (for certain radioactive materials). the half-life of a substance is 8.6 days and there is an amount equal to 15 grams now. what is the expression for the amount a(t) that remains after t days, and what is the amount of the substance remaining (rounded to the nearest tenth) after 37 days? hint: the exponential equation for half-life is a(t) = a0(0.5)t/h, where a(t) is the final amount remaining, a0  is the initial amount, t is time, and h is the half-life.