First, add the two measurements up, then subtract it from 8.
3 1/2 + 2 1/3
Convert to improper fractions:
7/2 + 7/3
Convert to denominators of 6:
21/6 + 14/6
Add the numerators:
35/6
Subtract from 8:
8 - 35/6
Convert 8 into a denominator of 6:
48/6 - 35/6
Subtract the numerators:
13/6
Convert to a mixed number:
2 1/6
So 2 1/6 of the board is left.