isabelle/valid/amc12b_2003_p9.thy (13 lines of code) (raw):
(*
Authors: Wenda Li
*)
theory amc12b_2003_p9 imports
Complex_Main
begin
theorem amc12b_2003_p9:
fixes a b ::real and f :: "real \<Rightarrow> real"
assumes "\<forall> x. f x = a * x + b"
and " f 6 - f 2 = 12"
shows "f 12 - f 2 = 30"
using assms by auto
end