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

State before:
A : Type ?u.3077
G : Type
inst✝¹ : Ring A
inst✝ : Group G
a x : G
⊢ x * a = 1 → a⁻¹ = x
Tactic:
sorry
State after:
no goals