rw [h1]
n : ℕ
h1 : 4 * (n - 1) + 1 + 6 = 2 * (2 * (n - 1) + 1 + 2) + 1
⊢ (4 * (n - 1) + 1 + 6) / 2 = 2 * (n - 1) + 1 + 2
n : ℕ
h1 : 4 * (n - 1) + 1 + 6 = 2 * (2 * (n - 1) + 1 + 2) + 1
⊢ (2 * (2 * (n - 1) + 1 + 2) + 1) / 2 = 2 * (n - 1) + 1 + 2