Since inches are out of 12 this would be
4 ft - 1 ft = 3 ft
3' 1" - 1 " = 3 '
3 feet is also 2 ft and 12 inches
2' 12" - 9 " = 2' 3"
So the answer is 2 feet and 3 inches
Hope this helps
-GoldenWolfX