Answer: 40 cm.
Step-by-step explanation: Perimeter involves adding all the sides of a shape to get the perimeter. So far, two sides of the scrapbook have been given, which are both 37 cm. 37 x 2 = 74, so that leaves us with two sides left, which are the lengths of the scrapbook. The total perimeter is 154, so if we subtract 74 from 154, we get 80. However, we have to split the 80 in half because we have two sides left. Therefore, the scrapbook's length is 40 cm for one side. I hope this isn't too confusing.
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