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

We see 4 and -4 and are tempted to say that this is not direct variation. However, these numbers cancel out, leaving us: $7x=3y$. Direct variation has the form y=kx. Thus, we need to simplify to isolate y to see if it is direct variation. Thus, we obtain: $7x=3y \\\ 7/3x=y$ This does have the form y=kx, so it is direct variation. k is the constant of variation, so we know that the thing x is being multiplied by, 7/3, is the constant of variation.