math
posted by jennie .
I am a third grader and have a homework of sketching and labeling all possible rectangles with perimeter of 30 cm and sides whose lengths are whole numbers. I am confuse, i need help please.

The formula for perimeter is,
P = 2w + 2 L
30 = 2w + 2L
30 = 2(w + l)
15 = w + l
So, for a perimeter of 30, you want to sketch rectangles that the width and length total 15.
Some possible rectangles,
14 + 1 = 15
13 + 2 = 15
12 + 3 = 15
11 + 4 = 15
10 + 5 = 15
9 + 6 = 15
8 + 7 = 15
Do you follow what I am doing?
I gave you a good start. Find the remaining sides that when added, equal 15.
Good luck! :) 
I will try. This will help me to start and gave me an idea. Thank you very much.

You're welcome.