Simplifying
(2a + 6 * 2)(3a + 3) + a

Multiply 6 * 2
(2a + 12)(3a + 3) + a

Reorder the terms:
(12 + 2a)(3a + 3) + a

Reorder the terms:
(12 + 2a)(3 + 3a) + a

Multiply (12 + 2a) * (3 + 3a)
(12(3 + 3a) + 2a * (3 + 3a)) + a
((3 * 12 + 3a * 12) + 2a * (3 + 3a)) + a
((36 + 36a) + 2a * (3 + 3a)) + a
(36 + 36a + (3 * 2a + 3a * 2a)) + a
(36 + 36a + (6a + 6a2)) + a

Combine like terms: 36a + 6a = 42a
(36 + 42a + 6a2) + a

Reorder the terms:
36 + 42a + a + 6a2

Combine like terms: 42a + a = 43a
36 + 43a + 6a2