Question 1:
To compute the cost of each mechanical pencil, we need to represent the cost of one mechanical pencil as \( x \). Since erasers cost $0.50 and Mr. Spears has a total of $25, we can write the equation as follows:
\[ x + 0.50 = 25 \]
The missing place in the original equation is the total cost of the mechanical pencil, which is represented by \( x \).
Question 2:
Stan tipped the waiter 20% on the reduced bill after the $12 dessert was removed. Based on the information given, the equation to determine the amount of the original bill \( b \) can be written as follows:
After removing the dessert, the reduced bill becomes \( b - 12 \). Since he tipped 20% on this reduced bill and the tip was $15, we can express this as:
\[ 0.20(b - 12) = 15 \]
So the filled-in equation will look like this:
\[ (b - 12) = \frac{15}{0.20} \]
You can also express it as:
\[ 15 = 0.20(b - 12) \]