I need help on this question (^~^;)ゞquestion: solve for x

ABCD is a parallelogram.
Thus,
AD = BC
We can equate the expressions and solve for x. Shown below:
[tex]\begin{gathered} AD=BC \\ 5x=15 \\ x=\frac{15}{5} \\ x=3 \end{gathered}[/tex]Answerx = 3