Question

The area of a rectangular deck is 680 square ft. The deck's width is 17 ft. What is its length?

Answer 1

A=LxW
680=Lx17
680/17=40
the length would 40 ft
:)

Answer 2

Area formula is length times width. You are given the total area and the width, so you only need to find the length. What your have been given can be set up as an equation:
17 ft times length ft (x) = 680 ft^2
x = 680/17 ft
x = 40 ft.

Hope that helps:)