help! The number of milligrams of a drug that remains in a patient’s system after t hours is given by the function A(t) = Ie^rt. Juan was given 500 milligrams of medicine which leaves his bloodstream at a rate of 20%. How much of the medicine remains in his system after 6 hours?

Question

phi · Answer

This equation means
$$ A(t)= 500e^{0.20t} $$

replace I (for initial amount?) with 500 mg, and the rate 20%  (as a decimal 20/100 or 0.20)
now replace t with 6 to find the amount of medicine in his system after 6 hours.

phi · Answer

"e"  stands for 2.71828  
and it should be a key on your calculator  (look for $e^x $ )