The triangle are similar . They are similar by SAS rules .Therefore the angles between the sides are the same .
[tex]\begin{gathered} 3x+18=4x+2 \\ 18-2=4x-3x \\ 16=x \\ x=16^{\circ} \end{gathered}[/tex]
Therefore angle A can be computed below
[tex]\angle A=3x+18=3(16)+18=48+18=66^{\circ}[/tex]
