[tex]\begin{gathered} DE=5x \\ KC=3x+12 \end{gathered}[/tex]
If KC and DE are congruent lines (The figure is a parallelogram) You can equal the given equations:
[tex]\begin{gathered} DE=KC \\ \\ 5x=3x+12 \end{gathered}[/tex]
Use the equation above to solve for x:
[tex]\begin{gathered} 5x-3x=12 \\ 2x=12 \\ x=\frac{12}{2} \\ \\ x=6 \end{gathered}[/tex]Then, the value of x is 6
