Answer: x=135°
Explanation:
Angles in a triangle always add up to 180° so to find the corner of the missing side next to x you need to do 58+77=135 then do 180-135=45°
So then, now we have the angle inside the triangle, we can now work out what x is.
Angles on a straight line always add up to 180° so you do 180-45=135° so x=135°.
Hope this helps :)