How do I solve this AP Chemistry problem on silver and bromine

Question

Silver ion and bromine ion precipitate into AgBr (s). The Ag+ concentration is about 0.065M. If the Br- concentration remains at 1.0×10^17M. What will be the remaining concentration of  Ag+ when the precipitation stops . (Ksp=7.7×10^13)

Answer 1

AgBr(s) <==> Ag⁺(aq) + Br^-(aq)

Ksp = 7.7x10^-13 = [Ag⁺][Br^-]  NOTE the correct exponent for the Ksp !!

A Br^- concentration of 1.0x10¹⁷?  Really?  I don't think so.

Plug in the CORRECT values and solve for [Ag⁺] and subtract from original [Ag⁺] to find remaining [Ag⁺]