Reina and Sam are multiplying (84)5 (73)9 Is either of them correct? Explain your reasoning.
Reina's Work: (84)5 (73)9 = 84 + 573 + 9 = 89712                                                 
 Sam's Work:  (84)5 (73)9 = 84⋅573⋅9 = 820727