1. Suppose you have a 5 unit by 5 unit square pool. How many 1 unit square paving stones will be needed to completely surround the pool with a one-unit wide border of paving stones? What if the pool was 20 units by 20 units?

2. Explain in words, using mathematical language, how you can determine the number of paving stones needed for an n by n unit pool. Express this relationship in the form of a rule that uses P as the total number of paving stones and n as the length of a side of the pool.

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