Answer:
The length of the shortest piece is
.
The length of the medium-sized piece is
.
The length of the longest piece is
.
Explanation:
The five-step method is GUESS method.
Given:
Length of copper wire,

Length of longest piece is 6 feet longer than the shortest one.
Length of the medium-sized piece is 3 times the shortest one.
Unknown:
Length of longest, medium-sized and shortest pieces of wire.
Let the length of shortest piece be
feet.
Therefore, the length of longest piece is equal to
.
And, length of the medium-sized piece is equal to
.
Evaluate:
Sum of lengths of longest, medium-sized and shortest pieces of wire is equal to the total length of wire. So,

Substitute and Solve:
Now, we have,
.
Substitute 1 for
and solve for each sizes of wire pieces. This gives,
Length of shortest piece =

Length of medium-sized piece =

Length of longest piece =

Therefore, the lengths of shortest, medium-sized, and longest pieces are
,
and
respectively.