if a ( a - 6 ) = 7 and b ( b - 6 ) = 7 , where a ≠ b , then a + b =
"i . e . if a = - 1 then b = 7 or if a = 7 then b = - 1 but in each case a + b = - 1 + 7 = 6 answer : option c"
subtract(subtract(subtract(subtract(add(add(6, 7), subtract(6, 7)), const_1), const_1), const_1), const_1)