We can see that it is an isosceles triangle, so than angles "R" and "T" are equals and the sum of the angles of a triangle must be equal to 180. Also by complementary angles we obtain that:
[tex](5x-50)+5x=180[/tex][tex]10x-50=180[/tex][tex]10x=130[/tex]
[tex]x=130/10[/tex][tex]x=13[/tex]
So, the right answer is C: x=13.
