Triangle proportionality theorem states that if a line is parallel to one side of a triangle and it intersects the other two sides, then it divides those sides proportionally
From the figure
DE is parallel to BA
That is DE || BA
Therefore, we have
CD / BD = CE / AE
CD = 9.5
BD = x
CE = 13.75
AE = 5.5
Substitute the above values into the above equation
9.5 / x = 13.75 / 5.5
Introduce cross multiplication
9.5 * 5.5 = 13.75 * x
52.25 = 13.75x
Re - arrange the equation
13.75x = 52.25
Divide both sides by 13.75
13.75x / 13.75 = 52.25 / 13.75
x = 52.25 / 13.75
x = 3.8
The answer is 3.8