



 
Hi Mia, Rectangles come in many shapes, long and thin, short and fat or even square. If your rectangle is $L$ cm by $W$ cm then you know that $L$ and $W$ are both positive and $L + W = 18$ cm but you don't know anything else about the sizes of $L$ and $W.$ In fact $L$ and $W$ can be any positive numbers wit $L + W = 18.$ Penny  


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