Answer:
MgCl₂+ Na₂CO₃ ==> MgCO₃ + NaCl
From a quick observation
You see that the right hand side of the eqn is deficient of Sodium and Chlorine
Simply Add a Coefficient of 2 to NaCl to balance it with the left.
Your answer now becomes
MgCl₂ + Na₂CO₃ ==> MgCO₃ + 2NaCl.✅