if a ( a - 1 ) = 20 and b ( b - 1 ) = 20 , where a ≠ b , then a + b =
"i . e . if a = 5 then b = - 4 or if a = - 4 then b = 5 but in each case a + b = - 5 + 4 = - 1 answer : option b"
subtract(subtract(subtract(subtract(add(add(1, 20), subtract(1, 20)), const_1), const_1), const_1), const_1)