Multiply:

(0.8a – o.5b) × (1.5a – 3b)

= 0.8a (1.5a – 3b) – 0.5b (1.5a – 3b)


= 1.2a2 – 2.4ab – 7.5ab + 1.5b2


= 1.2a2 – 9.9ab + 1.5b


10