Final answer:
The left over piece is 2ft.
Step-by-step explanation:
To find out how long a piece was left over, we need to subtract the total length of the 3 shelves from the length of the board. Each shelf is 4ft long, so the total length of the shelves is 4ft x 3 = 12ft. The length left over is the original length of the board (14ft) minus the total length of the shelves (12ft), which is 14ft - 12ft = 2ft. Therefore, the answer is 2ft.