You can put this solution on YOUR website! (x-6)^2+(x)^2=30^2
x-24=0 or x+18=0
x-24+24=0+24 or x+18-18=0-18
x=24 or x=-18
You listed this under "pythagorean theorem." If this is a problem about the sides of a triangle, then use x=24 because you can't have a negative length of a triangle.
Happy Calculating!!!