The perimeter of a rectangle garden is 48 feet. the length is 5 times the width.

what are the dimensions of the garden?

6 ft. by 8 ft
4 ft by 20 ft
3 ft by 9 ft
4 ft by 12 ft

I'll draw a diagram for you, so that it's easier to understand. 
First you have to understand that the perimeter is all the sides add up together.

Let's set up an equation, using l for the length, and w for the width.

5w + w = 48
Simplify
6w = 48
Divide by 6 on both sides
w = 8

Now the value we got is actually both widths (the green sides), so the width is actually 4. Which means that the length is 20. 

The answer is 4ft by 20 ft.

Hopefully this helps! If you have any more questions or don't understand, feel free to DM me, and I'll get back to you ASAP! :)

Igot the answer of 15.8 years.

Are you asking for 6 or 15?