Subtract the sum of the two angles from 180 degrees. The sum of all the angles of a triangle always equals 180 degrees. Write down the difference you found when subtracting the sum of the two angles from 180 degrees. This is the value of X.
x = (65)
- 20 + 55 + 40 = 115
- 180 - 115 = 65
- Therefore, x = 65
