Answer
$x = 4$
Work Step by Step
In a rectangle, diagonals are congruent and bisect one another; therefore, we can set the two bisected segments equal to one another:
$2x - 1 = x + 3$
Add $1$ to each side of the equation to move constants to the right side of the equation:
$2x = x + 4$
Subtract $x$ from each side of the equation to move variables to the left side of the equation:
$x = 4$
