
Doug C. answered 05/04/19
Math Tutor with Reputation to make difficult concepts understandable
If the area is 24cm2 and one of the dimensions is represented by x the other dimension must be 24/x.
Since the sides of the rectangle must be whole numbers there are a limited number of possibilities for x and 24/x.
1 x 24
2 x 12
3 x 8
4 x 6
6 x 4
...
Now they start repeating. Calculate the perimeter for each possibility to determine the maximum possible perimeter. For example the 3 x 8 rectangle has a perimeter of 22 cm. The 2 x 12 has P = 28cm. You can take it from there!