Answer:
To answer this question we will use the following diagram as reference:
Recall that the interior angles of an equilateral triangle measure 60 degrees each.
Now, notice that angles A and B form a linear pair, meaning that:
[tex]\angle A+\angle B=180^{\circ}.[/tex]
Substituting ∠A=60°, ∠B=8x° in the above equation we get:
[tex]60^{\circ}+8x^{\circ}=180^{\circ}.[/tex]
Solving the above equation for x, we get:
[tex]\begin{gathered} 60+8x=180, \\ 8x=180-60=120, \\ x=\frac{120}{8}, \\ x=15. \end{gathered}[/tex]
