Answer:
x = -9
Explanation:
The top angle would be 90 degrees due to the square.
The angles of a triangle add up to 180 degrees.
Set up the equation:
90 + 45 + x + 54 = 180
189 + x = 180
Subtract 189 from both sides:
x = -9
Now, if you need to solve for the angle, just plug x in:
-9 + 54 = 45 degrees
(In your case it is just looking for x so it would be x = -9)