Which would you use to determine how much money you have left over to save each month?

Ben (55kg) is standing on very slippery ice when junior (25kg) bumps into him. junior was moving at a speed of 8 m/s before the collision and ben and junior embrace after the collision. find the speed of ben and junior as they move across the ice after the collision. give the answer in m/s. describe the work you did to get the answer.