A rectangle flag had a width of 3 2/3 feet and area of 8 3/4 square feet. Which expression could be used to calculate the length, in feet, of the rectangle

Pretty sure it's 8 3/4 : 3 2/3.

Why?

So say you want to find the length of a rectangle who's area is 6, and the width is 2. You can divide the area by the width to find the length. 6/2 = 3.

Check: 2 * 3 = 6.

Back to the original question: 8 3/4 : 3 2/3.

Improper fractions: 35/4 : 11/3.

Switch division to multiplication and reciprocal: 35/4 * 3/11.

35/4 * 3/11 = 105/44.

Check:

105/44 * 11/3 = 1155/132 = 35/4 = 8 3/4

Length = 105/44