I got the wrong answer on this problem, what equation do I use to solve it?

Two carts mounted on an air track are moving toward one another. Cart 1 has a speed of 0.8 m/s and a mass of 0.46 kg. Cart 2 has a mass of 0.62 kg. (a) If the total momentum of the system is to be zero, what is the initial speed (in m/s) of Cart 2? (Enter a number.) m/s (b) Does it follow that the kinetic energy of the system is also zero since the momentum of the system is zero? Yes O No (c) Determine the system's kinetic energy (in ]) in order to substantiate your answer to part (b). (Enter a number.)