∠e and ∠f are vertical angles with m∠e=8x+8 and m∠f=2x+38 . what is the value of x?

We know that ∠E = ∠F because of the vertical angle theorem.

Using substitution we get 8x + 8 = 2x + 38

Solve for x.

8x + 8 = 2x + 38
8x = 2x = 30 <-- Subtract 8 from each side
6x = 30 <-- Subtract 2x from each side
x = 5 <-- Divide both sides by 6

So, x is equal to 5.