Aqueous calcium bromide was mixed with aqueous gold(i perchlorate, and a crystallized gold(i bromide product was formed. consider the other product and its phase, and then write the balanced molecular equation for this precipitation reaction.

Calcium bromide is CaBr2 
Gold(I) perchlorate is AuClO4 
Crystallized gold(I) bromide would be AuBr(s). beginning with those, your equation would be: 
CaBr2(aq) + AuClO4(aq) --> AuBr(s) 
Now, the other product would be calcium perchlorate that would remain soluble. Since perchlorate has a -1 charge, you will need 2 of that ion to balance a calcium ion. Also, since you have 2 Br- ions on the left, you will need 2 AuBr(s) on the right. All of that leads to: 

CaBr2(aq) + 2 AuClO4(aq) --> 2 AuBr(s) + Ca(ClO4)2(aq)