To determine how much space Robert will have left for his presentation after using the squares, we start by calculating the area of each square with a side length of \( s = 7 \) inches.
The area of one square (\( s^2 \)) is calculated as follows:
\[ s^2 = 7^2 = 49 \text{ square inches} \]
Since Robert is using 10 squares, the total area used by the squares is:
\[ 10s^2 = 10 \times 49 = 490 \text{ square inches} \]
Now, to find out how much space Robert will have left on the poster board, we subtract the area used by the squares from the total area of the poster board:
\[ 720 - 10s^2 = 720 - 490 \]
Calculating this gives:
\[ 720 - 490 = 230 \text{ square inches} \]
Therefore, the amount of space Robert will have left for his presentation is 230 square inches.