I thinks 5 because -2(x) = -2x and -2(5)=-10
So -2x=-10
-10/-2=5
X=5
We see that the second definition is not a good definition. We want both parts to have the same truth value, but we see that we can have two angles created by a ray that are not equal. That means the antecedent is false but the consequence is true, which means it's not an iff statement, and a bad definition in this context.
