[tex]JK=9x-11\\KL=5x+2\\JL=(9x-11)+(5x+2)=(9x+5x)+(-11+2)=14x-9\\\\JK+KL=JL\\\\\text{substitute}\\\\14x-9=10x+7\ \ \ \ |+9\\\\14x=10x+16\ \ \ \ |-10x\\\\4x=16\ \ \ \ |:4\\\\x=4\\\\JK=9x-11\to JK=9(4)-11=36-11=25[/tex]
