Answer:
x = 2
Step-by-step explanation:
The sum of the 3 angles in the triangle = 180°
Sum the 3 angles and equate to 180
6x + 15 + 90 + 63 = 180
6x + 168 = 180 ( subtract 168 from both sides )
6x = 12 ( divide both sides by 6 )
