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|rectangle 1|unknown|factor|term| edge|           
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|  length   |       |     2|   0|     |          
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|  width    |       |     1|   0|     |          
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|  area     |       |      |    |     |          
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|rectangle 2|unknown|factor|term| edge|           
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|  length   |       |     2|   3|     |          
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|  width    |       |     1|   0|     |          
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|  area     |       |      |    |     |          
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unknownS = 15 / rectangle 2's length term;       
for rectangle 1's length, rectangle 1's width,   
    rectangle 2's length and rectangle 2's width:
        edge$ = unknown$ X factor$ + term$.      
for rectangle 1's area and rectangle 2's area:   
    edge$ = length edge$ X width edge$;