if a ( a - 9 ) = 10 and b ( b - 9 ) = 10 , where a ≠ b , then a + b =
"i . e . if a = - 1 then b = 10 or if a = 10 then b = - 1 but in each case a + b = - 1 + 10 = 9 answer : option d"
subtract(subtract(subtract(subtract(add(add(9, 10), subtract(9, 10)), const_1), const_1), const_1), const_1)