Solve the following equation by factorisation:

(x + 1)(2x + 8) = (x + 7)(x + 3)

⇒ (x + 1)(2x + 8) = (x + 7)(x + 3)

⇒ 2x² + 8x + 2x + 8 = x² + 3x + 7x + 21

⇒ 2x² - x² + 10x + 8 = 10x + 21

⇒ x² + 10x - 10x = 21 - 8

⇒ x² = 13

⇒ x = $\pm \sqrt{13}$

Hence, x = $+ \sqrt{13}$ or x = $- \sqrt{13}$.

i.e., x = 3.61 or x = -3.61