import Mathlib

set_option maxHeartbeats 0

open BigOperators Real Nat Topology Rat

theorem amc12b_2021_p9 :
  (Real.log 80 / Real.log 2) / (Real.log 2 / Real.log 40) - (Real.log 160 / Real.log 2) / (Real.log 2 / Real.log 20) = 2 := by sorry