So the first thing to do is get the number of angles inside this pentagon, which is 540 degrees. One way to do this is that you know a pentagon is formed of 3 triangles and since there are 180 degrees in a triangle, 3x180=540
Then it is algebra
540=91+125+92+(3x-5)+(4x-8)
Simplify what you can and collect like terms
540=308+3x-5+4x-8
540=308+7x-13
Then move everything over to the one side so that the variable is isolated
