What is the displacement of the particle in the time interval 5 seconds to 8 seconds?

What are two different ways you could find the value of a? explain these methods.

Need only answer if you think you know it

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.