Answer & Step-by-step explanation:
1.5 litres = 1500ml
Small Milk Carton
300ml x 5 = 1500ml
£1.20 x 5 = £6
Large Milk Carton
500ml x 3 = 1500ml
£1.40 x 3 = £4.20
The best value for 1.5l (1500ml) is to purchase 3 large milk cartons, as it's cheaper (by £1.80) than buying a small milk cartons.