Answer:
The first piece is 5 inches long, while the second is 15 inches and the third one is 20 inches.
Explanation:
To determine the length of the 3 pieces, knowing that the total of the board is 40 inches, and that the second measures 3 times more than the first and the third measures 4 times more than the first, the following equation must be performed:
X + 3X + 4X = 40
8X = 40
X = 40/8
X = 5
Therefore, the first piece is 5 inches long, while the second is 15 inches and the third 20 inches.