Question

100 mL of 0.05 M NH3 solution are added to 60 mL of a 0.1 M solution of the same compound.Determine the concentration of the final solution.

Answer 1

Do you mean with "final concentration" you want composition of NH3 or do you want the dissociation components; i.e., NH4^+ and OH^-. I will assume you want final NH3 composition and not the dissociation parts.
mols #1 = M x L = ?
mols #2 = M x L = ?
final (NH3) = total mols NH3/total volume in L.