Hugh painted a room 60% pink and 40% orange. Before he began he had three full 1.5 litre pots of paint: one red, one yellow and one white. He mixed equal amounts of red and yellow to create the orange paint and he mixed red and white in the ratio 1 : 3 to create the pink paint. He made exactly the amounts of orange paint and pink paint that he needed. After doing so, he had 900 ml of the yellow paint left.