Theorem: Section5sheet2Solutions.WeakGroup.mul_eq_of_eq_inv_mul (FormalisingMathematics2024/Solutions/Section05groups/Sheet2.lean)

State before:
G : Type
inst✝ : WeakGroup G
a b c : G
h : b = a⁻¹ * c
⊢ a * b = c
Tactic:
apply mul_left_cancel a⁻¹
State after:
case h
G : Type
inst✝ : WeakGroup G
a b c : G
h : b = a⁻¹ * c
⊢ a⁻¹ * (a * b) = a⁻¹ * c

State before:
case h
G : Type
inst✝ : WeakGroup G
a b c : G
h : b = a⁻¹ * c
⊢ a⁻¹ * (a * b) = a⁻¹ * c
Tactic:
rwa [← mul_assoc, inv_mul_self, one_mul]
State after:
no goals