## Algebra 1: Common Core (15th Edition)

We know direct variation has the equation y=kx. Thus, we plug in the points and solve for k: $y=kx \\\\ 7.5=3k \\\\ k=2.5$ We substitute k back in to get the equation: $y=2.5x$ We now plug in x=12: $y=(2.5)(12)=30$