Answer:
after 3 hours :24mg left
after 4.25 hours:9 mg left
after 6 hours left
Step-by-step explanation:y for left mass of medicine
x for hour
y=60-20%*60 x y=60-12x
1.y=60-12*3=60-36=24
2.y=60-12*4.25=60-51=9
3.y=60-12*6=-12<0 No medicine is left.
y=