Factorise the following expression:
6p - 12q
∵ 6p = 2 × 3 × p = (2) × (3) × p = (2 × 3) × p
12q = 2 × 2 × 3 × q = (2) × 2 × (3) × q = (2 × 3) × 2 × q
∴ 6p - 12q = (2 × 3) [(p) - (2 × q)]
= 6[p - 2q]