Answer:
7 - x meters
Step-by-step explanation:
This is a difference of squares. The formula for difference of squares is
a^2-b^2 = (a-b)(a+b)
So plug the numbers we know into this formula.
Area = lw
49 - x^2 = (a-b)(7+x)
49 - x^2 = (7-x)(7+x)
The length is 7 - x meters.
