Problem: how much water must be added to 60 litres of milk at 1 1 ⁄ 2 litres for 20 so as to have a mixture worth 10 2 ⁄ 3 a litre ?
Rationale: "c . p . of 1 litre of milk = ( 20 × 2 ⁄ 3 ) = 40 ⁄ 3 ∴ ratio of water and milk = 8 ⁄ 3 : 32 ⁄ 3 = 8 : 32 = 1 : 4 ∴ quantity of water to be added to 60 litres of milk = ( 1 ⁄ 4 × 60 ) litres = 15 litres . answer c"
annotated_formula: divide(20, add(1, divide(1, 2)))