Final answer:
To find the area of the garden, first convert the width to yards. Then use the length in terms of width to write the formula for area of a rectangle. The final simplified expression for the area is 7x + 49 square yards, which is equivalent to the original expression.
Step-by-step explanation:
The first step to answer your question is to convert the width of the rectangular garden to yards, since its length is given in yards. As we know, 1 yard = 3 feet, so the width of the garden in yards is 21/3 = 7 yards. Now, the length of the garden is x yards longer than its width, meaning the length is (7 + x) yards.
To find the area of the garden, we use the equation for area of a rectangle which is length times width. So the area is (7 + x) * 7 yards^2. Simplifying this gives us 7x + 49 square yards. This simplified expression is equivalent to the original expression.
Learn more about Area of a Rectangle