Problem: how many even multiples of 65 are there between 649 and 1301 ?
Rationale: "650 = 10 * 65 1300 = 20 * 65 the even multiples are 65 multiplied by 10 , 12 , 14 , 16 , 18 , and 20 for a total of 6 . the answer is b ."
annotated_formula: add(divide(subtract(1301, 649), multiply(65, const_2)), const_1)