A railing for a deck requires pieces of redwood 4 ft 9 in, 13 ft 9 in, and 4 ft 3 in long.

What is the total length of material that is needed?

4 ft 9 in

13 ft 9 in
4 ft 3 in

Gives
21 ft 21 in
Since 12 inches make a foot,
21 in - 12 in = 9 in
Add another ft and keep the remaining inches

The total length needed is:
22 ft 9 in