Final answer:
To redesign the garden, Mr. Johnson needs to find the dimensions of the rectangle. Solving the equation, we find that the width is 10 feet and the length is 25 feet.
Step-by-step explanation:
To solve this problem, let's first define the variables.
Let's say the width of the rectangle is x feet.
According to the problem, the length of the rectangle is 5 feet less than three times its width, so the length is 3x - 5 feet.
The perimeter of a rectangle is given by the formula 2(length + width).
Since the perimeter is given as 70 feet, we can set up the following equation: 2(3x - 5 + x) = 70.
Simplifying the equation and solving for x, we get: 8x - 10 = 70.
Adding 10 to both sides and then dividing both sides by 8, we find that x = 10.
Therefore, the width of the rectangle is 10 feet, and the length is 3(10) - 5 = 25 feet.