Just an answer and a simple explanation are needed. Please and thank you!

Answer:
KL = 51
Step-by-step explanation:
1: Make an equation
[tex]10x -2 = 5x-8 + 7x -12[/tex]
the 10x is the JL line which is the whole line segment
2: start solving by getting all x to be on one side
[tex]10x-5x-7x = -8 -12 +2[/tex]
3: simplify
[tex]-2x = -18[/tex]
4: solve for x
[tex]x=9[/tex]
5: plug x back into KL
[tex]7(9)-12 = 51[/tex]