To find the amount of space Robert will have left for his presentation after using squares with 7-inch sides, we first need to calculate the area of one square, then the area of 10 squares.
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The area of one square with side length \( s = 7 \) inches is: \[ s^2 = 7^2 = 49 \text{ square inches} \]
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The area of 10 squares is: \[ 10s^2 = 10 \times 49 = 490 \text{ square inches} \]
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Now, subtract the area of the squares from the total area of the poster board: \[ 720 - 10s^2 = 720 - 490 = 230 \text{ square inches} \]
Therefore, the amount of space Robert will have left for his presentation is 230 square inches.
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