Answer:
x = 3
Step-by-step explanation:
This triangle is quadrilateral, so all three angles are going to be congruent here. Since the sum of angles in a triangle is always 180 degrees, (25x - 15) must be 60.
25x - 15 = 60
Add 15 to both sides: 25x = 75
Divide both sides by 25: x = 3
