Answer:
38cm
Step-by-step explanation:
1. The perimeter of a square can be found with the formula
2. Since its length and width are whole numbers, it must be either
1 x 18,
2 x 9 or
3 x 6
3. Using the formula in step 1, we can found that the perimeter in these cases are
38
22
18
respectively
4. Compare those perimeter we found in previous step, it's obvious that the greatest is 38. Solved.