Answer:
(a). The speed by which ball move afterwards
= 0.0533

(b). The speed of ball after collision
= 0.096

Step-by-step explanation:
Given data
= 0.4 kg
Velocity
= 10

= 75 + 0.4 = 75.04 kg
(a). From conservation of momentum principal
=

0.4 × 10 = 75.04 ×

= 0.0533

This is the speed by which ball move afterwards.
(b). Again from conservation of momentum principal
0.4 × 10 = - 0.4 × 8 + 75 ×

= 0.096

This is the speed of ball after collision.