Step-by-step explanation:
Given that,
According to the question,
[tex]\longrightarrow[/tex] Total length = Sum of the length of the two pieces
[tex]\longrightarrow[/tex] Total length = {x + (7x – 9)} feet
[tex]\longrightarrow[/tex] Total length = {x + 7x – 9} feet
[tex]\longrightarrow[/tex] Total length = (8x – 9) feet
Therefore, the total length of the board as a simplified expression in x is (8x – 9) feet.