Step-by-step explanation:
According to the question,
Basically,
[tex]\longrightarrow[/tex] Total length of the board = Sum of the length of the two pieces
[tex]\longrightarrow[/tex] Total length of the board = Length of 1st piece + Length of the 2nd piece
[tex]\longrightarrow[/tex] 7 feet = x feet + Length of the 2nd piece
[tex]\longrightarrow[/tex] (7 – x) feet + Length of the 2nd piece
Hence, we got the required answer!