Answer:
E
Step-by-step explanation:
The external angle of a triangle is equal to the sum of the 2 opposite interior angles.
8x + 15 is an external angle of the triangle, thus
8x + 15 = 3x + 20 + 4x + 5, that is
8x + 15 = 7x + 25 ( subtract 7x from both sides )
x + 15 = 25 ( subtract 15 from both sides )
x = 10
Thus none of them on the list → E
