Nothing.
The first is a measure of length or distance while the second is a measure of area. The two measure different things and, according to basic principles of dimensional analysis, conversion from one to the other is not valid.
133 square feet. Multiply length by width - the result is the area in square feet.
90-ft x 7-ft = 630 square feet
The equation would be Length x Width or in this case 7 ft. x 4.5 ft., which equals 31.5 square feet 7 x 4.5 = 31.5 ft2
We do not need the height for square feet, is we use that we would have volume. If it is 7 feet wide by 10 feet long it is 70 square feet.
75-ft x 7-ft = 525 square feet
49
7 ft x 4 ft = 28 ft2
16 ft x 7 ft = 16 x 7 square ft = 112 sq ft
84 square feet (or in shorter terms, 84 ft.2)
70 square feet. Multiply length by width - the result is the area in square feet.
63 Square Feet
91 square feet. Multiply the length by the width. The result is the area in square feet.