Problem: the food in a camp lasts for 40 men for 20 days . if 10 more men join , how many days will the food last ?
Rationale: one man can consume the same food in 40 * 20 = 800 days . 10 more men join , the total number of men = 50 the number of days the food will last = 800 / 50 = 16 days . answer : d
annotated_formula: divide(multiply(40, 20), add(40, 10))