#### Answer

The width of the rectangular garden is 10 yards.
The length of the rectangular garden is 29 yards.

#### Work Step by Step

Since the length is stated in terms of the width, we can let w represent the width.
The length of the garden is 1 yard shorter than three times its width.
Three times its width means 3w.
1 yard shorter than three times its width means 3w - 1.
So, the length of the garden is 3w - 1.
The formula for the perimeter of the rectangle is width + width + length + length
The perimeter of the rectangle is 78 yards, so we set up the following equation:
w + w + 3w - 1 + 3w - 1 = 78
8w - 2 = 78
8w = 80
Divide both sides by 8.
w = 10
The width of the rectangular garden is 10 yards.
The length of the rectangular garden is 3 $\times$ 10 - 1 = 29 yards.