In a parallelogram, the opposite sides are parallel and congruent (they have the same length).
So we can write the following equation comparing the sides x + 30 and 2x - 40:
[tex]\begin{gathered} x+30=2x-40 \\ 2x-x=30+40 \\ x=70 \end{gathered}[/tex]
So the value of x is 100, therefore the correct option is the second one.
