To solve the problem, let's begin by analyzing the equation given:
\[ b \cdot 8 + 25 = 500 \]
Here, \( b \) represents the number of beads Niel started with.
The operations involved are:
- Multiplication (b \cdot 8): This is used to determine the total number of beads used to make the 8 necklaces.
- Addition (+ 25): This operation is used to account for the 25 beads Niel bought after making the necklaces.
- Subtraction is needed to isolate \( b \) after we have obtained the sum of beads used and the ones bought.
- Division would come into play if we were determining how many beads were on each necklace after finding \( b \).
However, to directly identify how many beads he started with based on the equation provided, the relevant operations used in the solving process after writing the equation would be:
- First, you would subtract 25 from both sides to isolate the term with \( b \): \[ b \cdot 8 = 500 - 25 \]
- Then, you would divide both sides by 8 to solve for \( b \): \[ b = \frac{475}{8} \]
Considering the main operations used to solve the equation:
- The equation involves addition (for the beads bought) and division (to find out how many beads were initially present based on how many were used per necklace).
Therefore, the correct response is:
Addition and Division.