Answer:
45
Explanation:
Triangles equal up to 180 degrees therefore you do the following to solve this equation. So you have 80 and 55. So you add 80 to 55 and you get 135. Now you subtract 180 by 135 and that equals 45. So x=45. I will write it out as well.
55+80=135
180-135=45
x=45
To check.
80+55+45=180