Answer:
x = 8
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°
Sum the 3 given angles and equate to 180
13x - 8 + 7x + 4 + 3x = 180 , simplify left side
23x - 4 = 180 ( add 4 to both sides )
23x = 184 ( divide both sides by 23 )
x = 8
