no goals
α : Type u_2
β : Type u_1
γ : Type ?u.51778
ι : Sort ?u.51781
ι' : Sort ?u.51784
f✝ : α → β
s t : Set α
f : β → α
hf : Surjective f
eq : f ⁻¹' s = f ⁻¹' t
⊢ s = t
rw [← image_preimage_eq s hf, ← image_preimage_eq t hf, eq]