Explanation:
I'm assuming the equation is [tex]y = \frac{5}{7}x[/tex] which is the same as writing y = (5/7)x.
If so, then the constant of proportionality is the fraction out front: The value 5/7 is the coefficient of the term (5/7)x.
All direct proportion equations are of the form y = kx, where k is the constant of proportionality. Another example would be y = 12x and this time k = 12.
