math
posted by M.P.L on .
5yd 1ft 4in  2yd 2ft 8in

Do the subtraction like a normal (numerical subtraction) with borrowing. The only difference is when you borrow, you don't always get 10 from the next digit, but the appropriate number from the next unit.
For example,
4yd 2ft 4in  3yd 1ft 9in
Put them one on top of the other if you wish:
4yd 2ft 4in
3yd 1ft 9in
4in  9in , we need to borrow to get 1ft+4in=16in
so 16in  9in = 7in.
4yd 2ft 4in
3yd 1ft 9in

?yd ?ft 7in
Now 2ft on top becomes 1ft (after borrow), so 1ft1ft =0ft
4yd 2ft 4in
3yd 1ft 9in

?yd 0ft 7in
Finally, 4yd  3yd = 1 yd
4yd 2ft 4in
3yd 1ft 9in

1yd 0ft 7in
Proceed this way for your problem, and post for answer check if you wish.