Plz help me now girls m. eet fas. sst

Aportion of a line bounded by two points is defined as

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

The parabola x= √y-9 opens: a.)up b.)down c.)right d.)left