Ah, direct variation/proportion.
That is simply a linear equation with a y-intercept of 0.
So... let's solve this.
Simply put, a direct variation multiplies the x-value by a constant to get the y-value.
Let's take the point [tex](2, 48)[/tex] on this graph and solve for the constant of proportionality:
[tex]2a=48[/tex]
We easily solve that and get our answer of [tex]a=24[/tex]. (B)
