List the number of each type of atom on the right side of the equation MgS(aq)+2CuCl2(aq)→2CuS(s)+MgCl2(aq )

I get the left side correct, but not the right. Not sure what I am doing wrong.

The twister and runaway train are two coasters at the same amusement park. both coasters start at the same height. the coaster for the twister is twice the mass of the coaster for the runaway train. which roller coaster has greater gravitational potential energy at the start of the ride?