Explanation:
the side on the left of 155 is 180-155 which is 25
the one on top of 120 is 180-120 which is 60 so the one on the right of x is 180-(25+60) which is 95
now the value of x is 180-95 which is 85.
in the second one x=180-100 because the angle on the bottom of x is corresponding to the one that's equal to 100, so x=180-100 which is 80
for the first one x=85
the second one x=80