Answer:
Length of longest piece=21 in
Length of middle piece=18in
Length of shortest piece=12 in
Explanation:
We are given that
Total party-length =51 in
Let x be the length of longest piece
Length of shortest piece=x-9
Length of middle piece=6+x-9=x-3
We have to find the length of three pieces
According to question
Sum of length of three pieces=51in





Length of longest piece=21 in
Length of middle piece=21-3=18in
Length of shortest piece=21-9=12 in