Collisions mechanics question

A smooth spherical particle with mass 2.5 kg collides with a second smooth spherical

particle of mass 6kg. Before the collision, the ﬁrst particle has velocity 9ms^1

in the positive x-direction while the second particle has velocity 6ms^1 in the positive y-direction. At the instant of collision, the particles are so that the normals to their surfaces at the point of contact are ±n, where n

is a unit vector inclined at -pi/4 from the x-axis as shown. You may assume that the coeﬃcient of restitution e = 2/3 and that no other forces are involved. Determine the velocities v1,1 and v2,1 of the ﬁrst and second particles respectively, immediately after the collision.