C : Type u
inst✝¹ : Category C
inst✝ : NonPreadditiveAbelian C
X Y : C
a b : X ⟶ Y
⊢ 0 - (a - b) = 0 - a + b
C : Type u
inst✝¹ : Category C
inst✝ : NonPreadditiveAbelian C
X Y : C
a b : X ⟶ Y
⊢ -(a - b) = -a + b
rw [neg_def, neg_def]
C : Type u
inst✝¹ : Category C
inst✝ : NonPreadditiveAbelian C
X Y : C
a b : X ⟶ Y
⊢ 0 - 0 - (a - b) = 0 - a + b
C : Type u
inst✝¹ : Category C
inst✝ : NonPreadditiveAbelian C
X Y : C
a b : X ⟶ Y
⊢ 0 - (a - b) = 0 - a + b
conv_lhs => rw [← sub_self (0 : X ⟶ Y)]
no goals
C : Type u
inst✝¹ : Category C
inst✝ : NonPreadditiveAbelian C
X Y : C
a b : X ⟶ Y
⊢ 0 - 0 - (a - b) = 0 - a + b
rw [sub_sub_sub, add_def, neg_def]