Problem: the sum of the present ages of two persons a and b is 90 . if the age of a is twice that of b , find the sum of their ages 5 years hence ?
Rationale: "a + b = 90 , a = 2 b 2 b + b = 90 = > b = 30 then a = 60 . 5 years , their ages will be 65 and 35 . sum of their ages = 65 + 35 = 100 . answer : e"
annotated_formula: add(add(multiply(divide(90, 5), const_2), 5), add(divide(90, 5), 5))