Answer:
-9
Step-by-step explanation:
Since the opposite angles of both sides are congruent we know that the sides must be congruent also. Therefore, to solve for x we can set them equal to each other.
So the equation will be x+19=10, to solve we must isolate the variable.
First, subtract 19 from both sides
x+19-19=10-19
Then, simplify
x=-9
