Please do number 11 for me.

Rule-3 angles of a triangle =180 degrees . One angle is a right angle which is 90 degrees so the remaining 2 must equal 90 so the equation is so 90=(15x)+(8x-2) and now we just have to solve what is the value of x.
First we move -2 to the other side of the equation as +2 so we get 92=15x+8x next we put the 15x and 8x together and get 23 so 92=23 times x. So we divide 92 by 23 and the value of x is 4