Theorem: Tutorial.mul_inv_eq_iff_eq_mul (Tutorial/Advanced/Algebra/Lecture1.lean)

State before:
A : Type ?u.3816
G : Type
inst✝¹ : Ring A
inst✝ : Group G
a b c : G
⊢ a * b⁻¹ = c ↔ a = c * b
Tactic:
sorry
State after:
no goals