Elastic and Inelastic Collisions Practice Test

In space, two satellites collide elastically: $m_1=200,\text{kg}$ at $+1.5,\text{m/s}$, $m_2=300,\text{kg}$ at $-0.5,\text{m/s}$; calculate total momentum before and after.

A $1200,\text{kg}$ car at $+20,\text{m/s}$ hits a $3000,\text{kg}$ stationary truck; perfectly inelastic, negligible external impulse; what is $v_f$?