SnCl4+2HCl→A
A+2NH4 Cl→B
A and B ?
For this question go step by step. First think about the product of first reaction, You will get B easily.
Stannic chloride forms soluble chlorostannic acid when reacts withconc. HCl and in the presence of NH4Cl, it forms ammonium salt of this acid.
SnCl4+2HCl→H2SnCl6
Chlorostannic acid
H2SnCl6+2NH4Cl→(NH4)2SnCl6
Ammonium chlorostannate