Theorem: MyGroup.mul_one (LeanCourse/MIL/C02_Basics/solutions/Solutions_S02_Proving_Identities_in_Algebraic_Structures.lean)

State before:
G : Type u_1
inst✝ : Group G
a : G
⊢ a * 1 = a
Tactic:
rw [← mul_left_inv a, ← mul_assoc, mul_right_inv, one_mul]
State after:
no goals