When y varies inversely with x, we have the follow equation:
y = kx
k = constant of variation
To find k, plugin the values for y = -4 and x = 7 and then solve for k
y = kx
-4 = k7
-4 / 7 = k7/7
-4 / 7 = k
k = -4 / 7
Now that we found k, we write the equation that relates the variables like below
[tex]y = -\frac{4}{7}x[/tex]