A 0166 M NaBr and 0048 M NaCl mixture is going to be treated

A 0.166 M NaBr and 0.048 M NaCl mixture is going to be treated with AgNO₃. Calculate the % of bromide ion present when the choride starts to precipitate. K_sp (AgCl) = 1.8x10^-10; (AgBr) = 5.0x10^-13
Report your answer to two significant figures.

1) Which is the more soluble? We need to look at how the two substances ionize:

AgCl ---> Ag+ + Cl