For number 9, a triangle always adds up to 180 degrees.
Since we know that the triangle is a right triangle, we can state that 3x+11+25+90=180
3x=180-11-25-90
3x=54
x=54/3
x=18
For question 10, vertical angles are equal to eachother so 10=6x+12
10-12=6x
-2=6x
x=-2/6=-1/3
For question 11, 45 and 3x are supplementary angles.
45+3x=180
3x=180-45
3x=135
x=135/3
x=45
Your welcome
