Problem: when 4 is added to half of one - third of one - fifth of a number , the result is one - fifteenth of the number . find the number ?
Rationale: "explanation : let the number be 4 + 1 / 2 [ 1 / 3 ( a / 5 ) ] = a / 15 = > 4 = a / 30 = > a = 120 answer : d"
annotated_formula: divide(4, divide(divide(const_1, multiply(4, add(const_2, 4))), const_2))