have : n ≃ m := compare_eq.mp ‹compare n m = Ordering.eq›
ℕ : Type
inst✝⁴ : Core ℕ
inst✝³ : Induction ℕ
inst✝² : Addition ℕ
inst✝¹ : Sign ℕ
order_inst : Order ℕ
inst✝ : Compare ℕ
ord : Ordering
n m k j : ℕ
x✝¹ : compare n m = Ordering.eq
x✝ : compare k j = Ordering.eq
⊢ compare (n + k) (m + j) = Ordering.eq
ℕ : Type
inst✝⁴ : Core ℕ
inst✝³ : Induction ℕ
inst✝² : Addition ℕ
inst✝¹ : Sign ℕ
order_inst : Order ℕ
inst✝ : Compare ℕ
ord : Ordering
n m k j : ℕ
x✝¹ : compare n m = Ordering.eq
x✝ : compare k j = Ordering.eq
this : n ≃ m
⊢ compare (n + k) (m + j) = Ordering.eq