The triangles are similar and one can assume that LM and IJ have a ratio 2:1.
[tex]\begin{gathered} 2\cdot LM=IJ \\ 2\cdot(5x-21)=62-3x \\ 10x-42=62-3x \\ 10x+3x=62+42 \\ 13x=104 \\ x=\frac{104}{13}=8 \end{gathered}[/tex]Then the measurement IJ is:
[tex]IJ=62-3x=62-(3\cdot8)=62-24=38[/tex]