We have the following equation given:
[tex]7y-4x=0[/tex]We can solve for y like this:
[tex]7y=4x[/tex][tex]y=\frac{4}{7}x[/tex]And if we compare with the general formula:
[tex]y=kx[/tex]With k the constant of variation we see that the answer is k= 4/7
