Juice mixtures: conserve volume and each ingredient

Three brands of apple juice, A, B and C, each contain a certain percentage of pure juice and some artificial flavouring. The breakdown of the amount of juice and flavouring for each brand is summarised in the table below.

	A	B	C
Pure juice (%)	20	70	40
Artificial flavouring (%)	0.5	0.8	0.7

How many litres of each brand should be mixed to produce 300 litres of juice with 41.1% pure juice and 0.647% artificial flavouring?3 marks