I know I said I didn't know how to start my last question and them figured it out on my own but this one I have tried to work out and really can't get.

We have two carts that have magnets to keep them from touching. One cart is initially at rest and we push the second cart towards it. Because the two carts will not actually touch, the collision is elastic. Use the data given to find all the unknowns. Note that v1' is the velocity of cart 1 after the collision.
Mass 1: .51 kg
Mass 2: .50 kg
V1: 1.2 m/s

Sorry the unknowns are

V1'= ?
V2'= ?
P1= ?
P1'=?
% difference =?
KE1'= ?
KE2' = ?
% difference = ?