A 189 square foot rectangular office has a length of 21 feet. What is the width of the office?

The formula for this problem would be area=length * width

Seeing as you already have the area, the rest should be simple since you can just plug in the numbers.

area = 189 length = 21

189 = 21 * x

You would divide the 21 from both sides which will give you the width.

9 = x 9 feet