show (b * sgn a)//(a * sgn a) ≃ (d * sgn c)//(c * sgn c)
ℕ : Type
inst✝³ : Natural ℕ
ℤ : Type
inst✝² : Integer ℤ
a b : ℤ
denominator_positive✝¹ : AP (Positive b)
c d : ℤ
denominator_positive✝ : AP (Positive d)
inst✝¹ : AP (c//d ≄ 0)
inst✝ : AP (a//b ≄ 0)
x✝ : a//b ≃ c//d
this✝ : Integer.Nonzero a
this : Integer.Nonzero c
⊢ (a//b)⁻¹ ≃ (c//d)⁻¹
ℕ : Type
inst✝³ : Natural ℕ
ℤ : Type
inst✝² : Integer ℤ
a b : ℤ
denominator_positive✝¹ : AP (Positive b)
c d : ℤ
denominator_positive✝ : AP (Positive d)
inst✝¹ : AP (c//d ≄ 0)
inst✝ : AP (a//b ≄ 0)
x✝ : a//b ≃ c//d
this✝ : Integer.Nonzero a
this : Integer.Nonzero c
⊢ (b * sgn a)//(a * sgn a) ≃ (d * sgn c)//(c * sgn c)