Note that when you calculate the KE, you are already given the speeds for the particles before the collision and the speed of the green particle after the collision. So for them there is no need to use components, just use KE = 1/2mV^2, where V is the given speed of the particle.
For the speed of the red particle after the collision, you'll have to figure that out. Using momentum equations, you can solve for Vx & Vy for that particle. Then you can calculate its KE either by first finding the total speed (V^2 = Vx^2 + Vy^2) or just by using the components of its velocity:
KE = 1/2mV^2 = 1/2mVx^2 + 1/2mVy^2.