Hello from MrBillDoesMath!
Answer: x = 6
Discussion:
A quadrilateral is a parallelogram if and only if the diagonals bisect each other. In our case the two unlabeled line segment (comprising the diagonal) have a single tick meaning they have the same length. So that diagonal is bisected by the other diagonal. The trick is to find the value of "x" such that the remaining diagonal is bisected. This gives us:
3x = 4x -6
Add 6 to each side:
3x + 6 = 4x
Subtract 3x from each side:
6 = 4x - 3x = x
So x = 6
Regards, MrB
