Points (1,15) and (5,3)
Find the slope (m)
[tex]m=\frac{y2-y1}{x2-x1}[/tex]where:
(x1,y1) = (1,15)
(x2,y2) = (5,3)
Replacing:
[tex]m=\frac{3-15}{5-1}=\frac{-12}{4}=-3[/tex]the function has a slope m= -3
slope intercept form:
y=mx+b
Where
m= slope
so, the correct function is
y=-3x+18 (A)