Answer:
Step-by-step explanation:
By the Triangle Angle-Sum Theorem, the angles of a triangle add up to equal 180, regardless of the size of the triangle. We are given the angle measures, so adding them together and setting them equal to 180 is
60 + 3x + x + 20 = 180 and, combining like terms,
4x + 80 = 180. Subtracting 80 from both sides,
4x = 100 so
x = 25
