Start off by converting yards to feet so you can work with the same units. Since 1yd=3ft, 8yd=24ft and 5yd=15ft.
Next, add 5 feet to the the length because the problem states that it is actually 5 feet longer. The length becomes 29ft (24+5).
Subtract 2 feet from the width because it is stated that the garden is actually 2 feet narrower. The width becomes 13ft (15-2).
So the dimensions in feet are: l=29 and w=13.
The problem also asks for the dimensions in yards so divide the length and the width by three to find them in yards. You get: l=9.6667 and w=4.3333.
Hope this helps!