The segment bisector of line JK would be L since it passes through M
How to find JM is that you would have to solve 3x+15=8x+25 to get x and once you find x you just plug it into the equation for JM, 3x+15
3x+15=8x+25 (subtract 8x on both sides)
-5x+15=25 (subtract 15 on both sides)
-5x=10 (Divide on both sides)
x=-2
Plug that in:
3(-2)+15
-6+15
JM=9