Chapter 2 Linear Equations and Functions - 2.5 Model Direct Variation - 2.5 Exercises - Skill Practice - Page 109: 26

-36

We plug in the given point to find the constant of variation. Since the equation will be for direct variation, we can then plug this in for $a$ in the equation $y=ax$. (Note, the y-intercept is 0). Hence, we find: $$ -2 =-18a \\ a=\frac{1}{9}$$ Thus: $$y=\frac{1}{9}x$$ When $y=-4$: $$x =-4\times 9=-36$$