Given:-
[tex]\angle BCD=51[/tex]To find the value of x.
Since the corresponding opposite angles are equal and also the sum of angles inside a triangle is 180 degrees. we get,
[tex]\begin{gathered} 14x+4+55+51=180 \\ 14x+110=180 \\ 14x=180-110 \\ 14x=70 \\ x=\frac{70}{14} \\ x=5 \end{gathered}[/tex]So the required value of x is 5.