## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$$y=.5x$$
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: $$a=\frac{10}{20}=.5$$ Thus, the equation is: $$y=.5x$$