The triangles are similar by the AA postulate, since one of the angles is a right angle and other is vertically opposite they are equal, so the other angle should be equal too.
Since the triangles are similar the ratio
[tex]\frac{50}{80}=\frac{5}{8}[/tex]
should hold for every side, then:
[tex]\frac{5}{8}=\frac{30}{x}[/tex]
Solving for x we have:
[tex]\begin{gathered} \frac{5}{8}=\frac{30}{x} \\ x=\frac{30}{\frac{5}{8}} \\ x=48 \end{gathered}[/tex]
Therefore, x=48.
