All angles on a triangle add up to 180. If it's a right triangle it would be set up like this: 90+3x-4=6x-5=180. You would subtract 90 from 180 and get 90 left. 3x-4+6x-5=90. Then you would add 5 and 4 to 90.....3x+6x=99. Then you add 3x and 6x then you would be left with 9x=99. Divide 99 by 9 and you get x=11.
