Interior angles of a triangle add up to 180 degrees, this means that
[tex]25+55+x=180[/tex]
where x denote the third angle. Then, we get
[tex]80+x=180[/tex]
by moving 80 to the right hand side, we have
[tex]x=180-80[/tex]
then, the answer is x=100, which corresponds to option B
