Since this triangle has two congruent angles/sides, we know that it is an isosceles. We can tell by looking at the markings on the triangles: The curves on both angles A and C indicate that they are congruent, and the markings on lines AB and CB also tell us that they are congruent.
To solve for x, we set up our equation like this:
Since we know that lines AB and CB are congruent, that means 4x - 20 is equal to 2x + 30.
To solve, we can first subtract 2x from both sides and add 20 to both sides.
Then, we divide both sides by 2 to isolate x.
We can check if our answer is correct by plugging in our value for x into both expressions and see if they equal the same thing.
