Solution:
Given:
[tex]\angle A\cong\angle BDA[/tex]
From the image,
[tex]\begin{gathered} \angle A=5x \\ \angle BDA=3x+30 \end{gathered}[/tex]
Paragraph proof:
[tex]\begin{gathered} Since\text{ it is given that }\angle A\cong\angle BDA,\text{ and }\angle A=5x,\angle BDA=3x+30,\text{ then:} \\ \begin{equation*} \angle A\cong\angle BDA \end{equation*} \\ 5x=3x+30 \\ 5x-3x=30 \\ 2x=30 \\ x=\frac{30}{2} \\ x=15 \end{gathered}[/tex]
Prove:
x = 15
