1. **State the problem:** We have a classroom floor and a closet floor combined with a total area of 71 square meters. The classroom is a rectangle with dimensions 7 m by 9 m. We need to find the area of the closet floor. 2. **Write down the known information:** - Classroom area = length $ \times $ width = $7 \times 9$ - Total area (classroom + closet) = 71 square meters - Closet area = ? 3. **Calculate the classroom area:** $$\text{Classroom area} = 7 \times 9 = 63$$ 4. **Use the total area to find the closet area:** $$\text{Closet area} = \text{Total area} - \text{Classroom area} = 71 - 63$$ 5. **Simplify:** $$\text{Closet area} = 8$$ 6. **Answer:** The area of the closet floor is 8 square meters. This problem uses the formula for the area of rectangles and the principle that the total area is the sum of the parts. By subtracting the classroom area from the total, we find the closet area.