Well if you notice, 48, x, and x are all on the same line, so they must add up to equal 180 degrees. So...
2x + 48 = 180 2x = 132 x = 66
So each x is equal to 66 degrees. Now we know the triangle is a right triangle, and the sum of all interior angles must be equal to 180 degrees for a triangle. So...
5 because you subtract 15x and bring it to 3x^2 and get 3x^2-15x=0. Then take out the gcf and you get 3x(x-5)=0. Since it can't be 0, x-5=0 , the answer is 5.
