EXPLANATION:
-We must first find the value of x in the given equation for AC=4y-48.
-After obtaining the value we must add the value of AD = 18
The exercise is as follows:
[tex]\begin{gathered} 4y-48 \\ 4y=48 \\ y=\frac{48}{4} \\ y=\frac{24}{2} \\ y=12 \end{gathered}[/tex]Now we must replace the value in the equation; is as follows:
[tex]\begin{gathered} 4y-48 \\ 4(12)-48 \\ 40-48 \\ -8 \end{gathered}[/tex]