Answer: Marcel needs 10.5 feet board.
Explanation:
It is given that Marcel is purchasing a board to build a bookcase.
The number of equal sections he needs = 6
The length of each section he needed = 17.5 feet
To find the required length of the board to divide in equal sections we need tot multiply the length of each section with the number of sections needed.
The length of board is required =

Hence, Marcel needs 10.5 feet board.