To fill in the missing place in the equation, we need to denote the cost of each bundle of mechanical pencils. Let \( x \) represent the cost of a bundle of mechanical pencils.
The equation you provided is:
\[ (x + 0.50) = 25 \]
Here \( 0.50 \) is the cost of a bundle of 10 erasers, and \( x \) would be the cost of a bundle of mechanical pencils.
To find the cost of a bundle of mechanical pencils, you would rearrange the equation:
\[ x = 25 - 0.50 \]
Now calculating \( 25 - 0.50 \):
\[ x = 24.50 \]
Thus, the cost of a bundle of mechanical pencils ( \( x \) ) is $24.50.
If you want the cost of each mechanical pencil, you would divide the cost of the bundle by the number of pencils in the bundle (10):
\[ \text{Cost per mechanical pencil} = \frac{24.50}{10} = 2.45 \]
So, the missing place in the equation represents \( 24.50 \), which is the cost of the mechanical pencils bundle. Each mechanical pencil costs $2.45.