30 + 4x + 2 + 180 - (8 + 6x) = 180;The sum of all angles in a triangle is 180
32 + 4x - 8 - 6x = 0
2x = 24
x = 12
Bolded part, explanation: On a straight line, the sum of all angles is 180 degrees. We have the value of outside the triangle, the exterior angle, which, when is added with interior angle, gives 180 degrees. So we substract 8 + 6x from 180, that's the third angle in a triangle.