In this question, we have to use the exterior angle theorem, which states that
Exterior angle is the sum of non adjacent interior angles.
So we will get
[tex] 3x+20+4x+5 =8x+15 [/tex]
Combining like terms
[tex] 7x+25= 8x+15 [/tex]
[tex] 25-15 = 8x-7x
\\
x = 10 [/tex]
And when x =10, exterior angle is
[tex] 8(10)+15 = 95 degree [/tex]
