$600$ square feet.
Work Step by Step
Since the patio has a form of a rectangle, its area is the product of its two sides, thus the area is: $20\cdot30=600$ square feet.
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.