Two elements A (at mass 16) and B (at mass 14) combine to form compounds x,y and z. The ratio of different masses of B which combine with a fixed mass of A in x, y and z is 1:3:5. If 32 parts by mass of A combine with 84 parts by mass of B in x, then in z, 16 parts by mass of A will combine with ______ parts by mass of B