see the attached figure to better understand the problem
we know that
[tex]JM=JL+LM[/tex]
Solve for JL
[tex]JL=JM-LM[/tex]
we have
[tex]JM=(5x-8)\\LM=(2x-6)[/tex]
substitute
[tex]JL=(5x-8)-(2x-6)[/tex]
[tex]JL=5x-8-2x+6[/tex]
[tex]JL=3x-2[/tex]
therefore
the answer is
[tex]JL=3x-2[/tex]
