Hi there!
From the given information, we can infer that the inner quadrilateral has equal side lengths of x and 2x-3.
We can turn this into a mathematical equation with 1 variable.
x = 2x - 3
Subtract both sides by 2x
-x = -3
Multiply both sides by -1
x = 3
Have an awesome day! :)
~collinjun0827, Junior Moderator