37x+24y+6-11x+2y+7=26x+26y+13=13*(2x+2y+1). 13*(2x+2y+1)/13=2x+2y+1.
37x+24y+6-(11x-2y-7)=37x424y+6-11x+2y+7=26x+26y+13=13*(2x+2y+13).
37x+24y+6-11x+2y+7=26x+26y+13=13*(2x+2y+1). 13*(2x+2y+1)/13=2x+2y+1.
37x+24y+6-(11x-2y-7)=37x424y+6-11x+2y+7=26x+26y+13=13*(2x+2y+13).