Eduardo is building a sandbox that has an area of 84 square feet. What are the possible whole number measurements for the length and width of the sandbox? Show work, please. (By the way, this is for anyone who wants extra points.)

Try this option:
1. note, that the number 84 is divided by numbers: 1;2;3;4;6;7;12;14;21;28;42 and 84. It means, that measurements of the length may be: 1;2;3;4;6;7;12;14;21;28;42;84 and for the width: 84;42;28;21;14;12;7;6;4;3;2;1.
2. according the numbers calculated in item 1, the possible number measurements for the length and width of the sandbox are (length; width):
1;84
2;42
3;28
4;21
6;14
7;12
12;7
14;6
21;4
28;3
42;2
84;1