Answer:
25
Step-by-step explanation:
So there is this property,
Sum of two angle of triangle = exterior angle
So based on this we can form an algebraic equation (NOTE: this is an equilateral triangle so all the sides are 60°)
[tex]4x + 20 = 60 + 60 \\ 4x = 120 - 20 \\ 4x = 100 \\ x = \frac{100}{4} \\ x = 25[/tex]
So it's option B.
