Heather P. answered 04/26/19
13+ Years Teaching & Tutoring Geometry in Middle/High Schools
It might help to start by graphing the points J & K. This will help you see what's happening visually.
The ratio statement (JK:KL=1:2) tells you that L is twice the distance from K as J is. You can then use the slope from J to K twice, to find L.
I hope this makes sense.
Please let me know if you have further questions.