Final answer:
The perimeter of a rectangular garden, when given the lengths of two adjacent sides, is calculated by doubling the sum of those sides using the expression P = 2(l + w).
Step-by-step explanation:
Perimeter of a rectangle can be expressed as P = 2(l + w), where l represents the length and w represents the width of the rectangle. In the case of a rectangular garden, if you know the lengths of two adjacent sides, you can calculate the perimeter by doubling the sum of these two sides. It's important to use the correct units when dealing with perimeter and area calculations to reflect the physical dimension being measured.