Use figure abcd below draw a line segment from point a to point c name and classify the triangles formed

Initially, Ball A of 10 kg will have velocity x, while Ball B of 30 kg has velocity -10 m/s.
After collision, Ball A will have a velocity of -30 m/s, while Ball B will have velocity 10 m/s. We assume their masses do not change.
(10 kg)(x m/s) + (30 kg)(-10 m/s) = (10 kg)(-30 m/s) + (30 kg)(10 m/s)
10x - 300 = -300 + 300
x = 30 m/s (to the right)