Answer:
The const. of variation / proportionality is thus 4.
Step-by-step explanation:
Direct variation is modeled by y = kx, where k is the constant of proportionality. The associated line passes thru the origin, and so the y-intercept, b, is zero.
If we go from (3, 12) to (9, 36), x increases by 6 and y increases by 24. Thus, the slope, same as the constant of proportionality in this case, is
k = rise / run = 24 / 6, or 4. The const. of variation / proportionality is thus 4.
