100 POINTS PLEASE answer ASAP

Aboxcar traveling at 12 m/s approaches a string of 5 identical boxcars sitting stationary on the track. the moving boxcar collides and links with the stationary cars and they all move off together along the track. what is the final speed of the cars immediately after the collision? (you may take the mass of each boxcar to be 18,537 kg.)

Under normal conditions, describe how increasing the temperatures effects the solubility of a typical salt

What’s #16 asking me and how do i solve it?