Theorem: MyGroup.mul_left_cancel' (IIScExperiments/Solutions/GroupTheorySolutions.lean)

State before:
G : Type
inst✝ : MyGroup G
a b c : G
h : a * b = a * c
⊢ b = c
Tactic:
rw [← one_mul b, ← inv_mul_self a, mul_assoc, h, ← mul_assoc, inv_mul_self, one_mul]
State after:
no goals