Answer:
5 cm
Explanation:
If Claire cut out a square out of a larger square, then the area of the square she cut out added to the leftover area would equal the original area of the bigger square. So we add the cut out square (9 cm²) to the leftover area (16 cm²) to get 25 cm². So 25 cm² = L². If we take the square root of both sides, we get L = 5 cm.