Answer
Shorter piece is 4 feet, longer piece is 8 feet.
Work Step by Step
If the longer piece is twice the size of the shorter piece, whose length is x, then the longer piece's length is 2x. The equation for the lengths is written as:
x + 2x = 12
Solve for x:
3x = 12
x = 4
The short piece is x = 4 feet, and the longer piece is 2x = 2(4) = 8 feet.