To determine how much space Robert will have left on his poster board after using squares of size 7 inches, we first need to calculate the area of the 12 squares.
Each square has an area calculated as follows:
\[ \text{Area of one square} = \text{side} \times \text{side} = 7, \text{in} \times 7, \text{in} = 49, \text{square inches} \]
Now, since Robert wants to use 12 squares, we calculate the total area covered by the squares:
\[ \text{Total area of 12 squares} = 12 \times 49, \text{square inches} = 588, \text{square inches} \]
Next, we find the area of the original poster board, which is 720 square inches. We can now find the remaining area by subtracting the area taken up by the squares from the total area of the poster board:
\[ \text{Remaining area} = \text{Total area of poster board} - \text{Total area of 12 squares} = 720, \text{square inches} - 588, \text{square inches} = 132, \text{square inches} \]
So, the space Robert will have left for his presentation is:
\[ \boxed{132}, \text{square inches} \]
Regarding the expression \(720 - 10s\) with \(s = 7\), we can substitute \(s\) into the equation:
\[ 720 - 10s = 720 - 10(7) = 720 - 70 = 650 \]
However, note that this calculation does not directly correspond to the area occupied by the squares. The relevant calculation for the space left would focus on \(720 - 588\), which has already been provided as the final answer. The area left is indeed \(132\) square inches, while the result from \(720 - 10s\) does not represent the same scenario.
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