a b c : Int
h✝ : a + b < c
h : a + b + -b < c + -b
⊢ a < c - b
a b c : Int
h : a + b < c
⊢ a < c - b
have h := Int.add_lt_add_right h (-b)
no goals
a b c : Int
h✝ : a + b < c
h : a + b + -b < c + -b
⊢ a < c - b
rwa [Int.add_neg_cancel_right] at h