Further mechanics chapter 5 help

Hello, i’m on question 3 of the mixed exercise 5 from the pearson edexcel further mechanics 1 book, and i’m getting a different answer to the one in the book but i’m not seeing how. i was just wondering if anyone could help!
The question is:
A smooth ball of mass 500g is moving in the xy plane and collides with a smooth fixed vertical wall which contains the line x + y = 3. The velocity of the call just before impact is ( -4i -2j) ms^-1. the coefficient of restitution is 0.5. Find the velocity of the ball immediately after impact.

Thank you for any help!