Answer:
x=25
Step-by-step explanation:
we know that
The triangle external angle theorem states that: An exterior angle of a triangle is equal to the sum of the opposite interior angles
In this problem
m∠9=m∠7+m∠8
substitute the given values
[tex](6x-20)\°=30\°+4x\°[/tex]
solve for x
[tex]6x-4x=30+20\\2x=50\\x=25[/tex]
