A milkman uses three containers forselling milk, their capacities being 40 L, 30 L and 20 respectively. He fills respectively 87.5%, 80% and 90% of the containers with a mix of milk and water in the ratios, 3: 2, 5: 1 and 7:2 respectively. What is the ratio of the total quantity of milk to that of water carried by him?

In container A milk and water = 87.5% of 40 = 35

In container A milk = $$\frac{3}{5}\times35 = 21$$ and In container A water = $$\frac{2}{5}\times35 = 14$$

In container B milk and water = 80% of 30 = 24

In container B milk = $$\frac{5}{6}\times24 = 20$$ and In container B water = $$\frac{1}{6}\times24 = 4$$

In container C milk and water = 90% of 20 = 18

In container C milk = $$\frac{7}{9}\times18 = 14$$ and In container C water = $$\frac{2}{9}\times18 = 4$$

Now, ratio of the total quantity of milk to that of water carried by him = (21+20+14) : (14+4+4) = 55:22 = 5 :2