Subtract the difference between the total length of the board (8 feet) and 7 feet 10 3/4 inches. To make it easier, convert both measurements to inches.
1 foot= 12 inches
TOTAL LENGTH:
multiply total length by number of inches in 1 foot.
8 feet * 12 inches= 96 inches
LENGTH TO BE CUT:
7 feet * 12 inches=84 inches
84 + 10 3/4 inches= 94 3/4= 94.75
FIND DIFFERENCE:
=96 - 94.75
=1.25 inches
=1 1/4 inch
ANSWER:
1 1/4 inch is cut off each board.
Hope this helps! :)