ANSWER:
The value of the angle A is 55°
STEP-BY-STEP EXPLANATION:
Angles opposite equal sides are angles that are also equal.
Therefore, in this case A and C are equal angles, therefore we can do the following equation:
[tex]\begin{gathered} A=C \\ 3x+40=x+50 \end{gathered}[/tex]
Solving for x:
[tex]\begin{gathered} 3x-x=50-40 \\ 2x=10 \\ x=\frac{10}{2} \\ x=5 \end{gathered}[/tex]
Now we replace the value of x, in A and we are left with:
[tex]\begin{gathered} A=3\cdot5+40 \\ A=15+40 \\ A=55 \end{gathered}[/tex]
