isabelle/valid/mathd_numbertheory_232.thy (16 lines of code) (raw):
(*
Authors: Wenda Li
*)
theory mathd_numbertheory_232
imports Complex_Main "HOL-Computational_Algebra.Computational_Algebra"
"HOL-Number_Theory.Number_Theory"
begin
theorem mathd_numbertheory_232:
fixes x y z::nat
assumes "x<31" "y<31" "z<31"
and "[x *3 = 1] (mod 31)"
and "[y * 5 = 1] (mod 31)"
and "[z * (x + y) =1] (mod 31)"
shows "z = 29"
sorry
end