I needdd help. Thanks :)

Apatient is given 50 mg dose of medicine the medicines effectiveness decreases every hour at a constant rate of 40% what is the exponential decay function that models this scenario how much medicine will be left in the patients system after 2 hours

At your job you're paid $50 per week plus $3 per sale at least how many saled do you need to make in order to have over $250

In a class of 77, there are 44 students who play soccer. if the teacher chooses 33 students, what is the probability that none of the three of them play soccer?