Answer:
if it is a rectangle then the sides of the width would be the same. Also with the sides of the length. So add the widths, 10+10=20. Subtract 20 from 90, 90-20=70. Divide 70 by 2, 70÷2=35.
The length would be 35 feet.
----A drawing shows a rectangular plot of dirt with 10 plants in 2 rows inside it. The top side is labeled question mark feet. The right side is labeled 10 feet. Below, text says perimeter = 90 feet.