You'll find the attached formulas quite helpful.
The slope of a line, denoted "m" is:
m=(y2-y1)/(x2-x1), where (x1,y1) and (x2,y2) are any two points on the line.
m=(-4--3)/(9-5)
m=-1/4
So the slope is negative one quarter.
Seeing that the human has 3 meals a day they would consume 666.66 calories per meal