Abowling ball has an initial momentum of +30 kg m/s and hits a stationary bowling pin. after the collision, the bowling ball leaves with a momentum of +13 kg • m/s.
what is the magnitude of the final momentum of the bowling pin if it has a mass of 1.5 kg?

Momentum should be conserved. The momentum of both objects must balance with their initial and final momentum.

Let m1 and v1 be the mass and velocity of the bowling ball

And m2 and v2 be the mass and velocity of the bowling pin

(m1v1)i + (m2v2)i = (m1v1)f + (m2v2)f

30 kg m/s + (1.5 kg)(0 m/s) = 13kg m/s + 1.5v2f

V2f = 11.33 m/s

So the momentum = 1.5 kg(11.33 m/s) = 17 kg m/s