What is the velocity of particle x with reference to Y?

[Alpha123]

Homework Statement

Particle X moves with a velocity of 15 m/s[R]. Particle Y moves with a velocity of 5.0 m/s[L]. What is the velocity of particle X with reference to particle Y? The correct answer is 20 m/s (R).
I do not understand what velocity in reference to particle Y means, and how to find it.

Homework Equations

d= (vi)t + 1/2 at^2
(vf)^2= (vi)^2 + 2ad
vf= vi + at
a=(vi+vf)/2 X t

The Attempt at a Solution

I have drawn the vectors ( not sure if correctly done), but i do not know what my next step is.

 

[Alpha123]

the correct answer is 20

 

[RyanH42]

I do not understand what velocity in reference to particle Y means, and how to find it.

Referance frame means you need to take that point which make observation.In this situation referance frame Y means, Y car is your observer.You don't need to find anything about referance frame, its just a concept.I think you don't now the idea of referance frame.I will recommend you watch this.It will help you the understand of idea.Then you may do the question yourself.And the equations which you wrote are not going to help us to solve this question.They are unnecessary.

 

[RyanH42]

If you didnt understnd again tell me which I can help you to solve the question

 

[Alpha123]

thank you ! I understood it .