if the number 1 is the output for carmichaels function machine shown right, how can you find out what number was dropped in? find the number(s) that could have been dropped in ?

Sanderson is having trouble with his assignment. his shown work is as follows: − 3 7 7 3 = − 3 7 × 7 3 = − 21 21 = −1 however, his answer does not match the answer that his teacher gives him. complete the description of sanderson's mistake. find the correct answer.