Please help. This quilt has 3 borders and they are to be mitered. Now, I have read that all the border strips should be sewn together and mitered as one. That's all fine and dandy but I'm not sure how to get them all the right length. The first border in 3 1/2 inches, the second border is 2 1/2 inches and the outside border is 5 inches. I did the math and have the inside borders cut and they appear correct. Do I just cut the next ones the same size or do I recalculate the quilt size, which is 60 x 80 1/2 in the middle and add on 3 1/2 inches for the next border and then recalculate and add on 5 inches for the outside one? And do I calculate in the finished width of the border or the actual width? This is too hard and I may never mitre another border!