The angles in a triangle add up to 180, so its
5x+2+6x-10+4x+8=100, then you combine it, so its
15x=180, then divide 180 by 15, and you get 12.
Then insert that into each equation.
4(12)+8= 56
5(12)+2= 62
6(12)-10= 62
They all add up to 180 and two of the angles have the same measure, which makes it an isosceles triangle.