To find the space Robert will have left for his presentation after using squares with 7-inch sides, we need to evaluate the expression:
\[ 720 - 10s^2 \]
where \( s = 7 \).
First, let's calculate \( s^2 \):
\[ s^2 = 7^2 = 49 \]
Next, we multiply by 10:
\[ 10s^2 = 10 \times 49 = 490 \]
Now we can substitute this value back into the original expression:
\[ 720 - 10s^2 = 720 - 490 = 230 \]
Thus, the space Robert will have left for his presentation is:
230 square inches.