Answer
The remaining board piece will be 3 (7/8) feet long
Explanation
Mia's board is 15 (1/2) feet long.
He cut three pieces off the board with each board measuring 3 (7/8) feet long.
The key to this is to first convert the values given in mixed fractions as improper fractions.
3 (7/8) = (31/8)
15 (1/2) = (31/2)
Then, the three pieces each had a length of 3 (7/8)
1 piece = 3 (7/8) feet = (31/8) feet
3 pieces = 3 × (31/8) = (93/8) feet
So, taking this out of 15 (1/2) long board will leave
[15 (1/2)] - (93/8)
= (31/2) - (93/8)
To do that, we need to take the LCM of these two denominators
[tex]\begin{gathered} \frac{31}{2}-\frac{93}{8} \\ =\frac{124-93}{8} \\ =\frac{31}{8} \end{gathered}[/tex]
The remaining board piece will be
(31/8) = 3 (7/8) feet long
Hope this Helps!!!