If you begin by sketching the garden with the dimensions:15yd. by 6 yd.Next add a border of 2 yd all around the garden plot sketch. Now you have an overall dimension of garden and border of 19yd by 10 yd. (You have added 4 yds to each original garden dimension)What you are looking for is the area of the border only, so if you multiply the overall dimensions of 19 by 10 you get 190 square yds.However you do not want to include your garden area which is 15 by 6 so you need to subtract this area from the overall area. 190 yd^2 minus the garden area of 90 yd^2 = 100 yd^2This leaves you with the border's area of 100 yd^2.Your answer is that you can add a 2 yard border around the entire garden plot.