Answer:
x = 28
Explanation:
The triangle is isosceles, meaning that the two base angles (x + 20) are congruent. We can then create an equation that states: (x + 20) + (x + 20) + 3x = 180. Simplifying this, we get 5x + 40 = 180. We can then use reverse order of operations to solve it. Subtract 40 from both sides to get 5x = 140. We will then divide both sides by 5 to get x by itself, getting us the equation x = 28.