Formular for line graph is
[tex] y=mx+b [/tex]
Find the gradient first
[tex] { \frac{y1-y2}{x1-x2} } \\ \\ = { \frac{0-80}{0-10} } \\ \\ = { \frac{-80}{-10} } \\ \\ = 8 [/tex]
Substitude the gradient to the formular
[tex] 80=8(10)+b \\ \\ b=0 [/tex]
∴ m=8h is the equation of the graph.
Answer is C.
