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)
