Problem: find the average of all prime numbers between 30 and 50
Rationale: "prime numbers between 30 and 50 are 37 , 41 , 43 , 47 required average = ( 37 + 41 + 43 + 47 ) / 4 = 168 / 4 = 42 answer is b"
annotated_formula: divide(add(add(add(30, const_1), add(add(const_4.0, const_1), const_2)), add(subtract(50, const_4.0), subtract(50, const_2))), 30)