Let's analyze the given quadrilateral to find the length JQ. Keep in mind we have been told that the figure is a rectangle.
Since the given figure is a rectangle, we know that all the segments of the diagonals are congruent.
JQ=QM = NQ=QK
We can use this fact to substitute the given expressions, NQ=2x+3 and QK=5x-9, to find the value of x.
NQ=QK ⇔ 2x+3 = 5x-9
We can use this equation to solve for x.