Problem: a and b can do a piece of work in 30 days and 30 days respectively . they work together for 10 days and b leaves . in how many days the whole work is completed ?
Rationale: "explanation : ( a + b ) ’ s 10 days work = 10 [ 1 / 30 + 1 / 30 ] = 10 [ 1 + 1 / 30 ] = 2 / 3 a complete remaining work in 2 / 3 * 30 = 20 total work = 10 + 20 = 30 days answer : option a"
annotated_formula: divide(subtract(10, add(divide(10, 30), divide(10, 30))), divide(10, 30))