Factorise:
22y – 33z
We have 22y = 2 × 11 × y
33z = 3 × 11 × z
∴ 22y - 33z = [2 × (11) × y] + [3 × (11) × z]
= (11)[2 × y - 3 × z]
= 11[2y - 3z]