In any triangle, the sum of the interior angles of two vertices is equal to the exterior angle of the other vertex.
Using this property, we can write the following equation:
[tex]\begin{gathered} \text{ABC+BAC=ACD}_{} \\ (4y+8)+(5y+3)=146 \\ 9y+11=146 \\ 9y=146-11 \\ 9y=135 \\ y=\frac{135}{9} \\ y=15 \end{gathered}[/tex]
The value of y is equal to 15, therefore the correct option is A.
