Need help asap please

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

What values of x satisfy the inequality x^2-9x< 0? how is your answer shown on the graph?

An equation in slope-intersept form the lines that passes thought (-8,1) and is perpindicular to the y=2x-17.