Go on then work out the the Na/K ratio.
It is quite simple really.
First, determine the amount of mol's of Cl.
You know that (simplified):
NaCl + KCl -> AgCl
In other words, all Cl is used by the Silver.
So you have.4.626 g - X g NaCl
+ X g KCl
= mols Cl = mols AgCl
58.443g/mol 74.551 g/mol
Once you solve for X you know the amount (in grams) of NaCl (4.626 - X) and KCl (X) in the original mixture, so the ratio is pretty easy from that point on.