Explanation
To find the greatest possible length of each piece, we need to find the greatest common divisor (GCD) of 18, 42, and 24.
Factors of 18: 1, 2, 3, 6, 9, 18
Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42
Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
The greatest common factor is 6.