The equation of a proportional relation between x and y with a constant of proportionality k is:
[tex]y=kx[/tex]If the constant rate of change is 7, then:
[tex]y=7x[/tex]If y=12, substitute that value into the equation and solve for x:
[tex]\begin{gathered} 12=7x \\ \Rightarrow x=\frac{12}{7} \end{gathered}[/tex]Therefore, if y=12 then the value of x is:
[tex]\frac{12}{7}[/tex]