To solve the problem, we need to find out how many beads Niel started with.
Let's denote the number of beads he started with as \( b \). According to the question, he used the beads to make 8 identical necklaces, which means he used \( 8b \) beads (if \( b \) is the number of beads for each necklace). After that, he bought 25 additional beads, giving him a total of 500 beads.
The equation can be understood as follows:
- \( 8b \) is the total number of beads used for the necklaces.
- He buys 25 more beads.
- The total thus becomes \( 8b + 25 \).
- This total equals 500 beads.
So the correct way to set it up is:
\[ 8b + 25 = 500 \]
Now, to solve for \( b \):
- Subtract 25 from both sides: \( 8b = 500 - 25 \)
- This simplifies the equation to \( 8b = 475 \).
- Then divide both sides by 8 to find \( b \): \( b = 475 / 8 \).
In this context, the operations involved to solve the equation \( 8b + 25 = 500 \) are subtraction and division (to isolate \( b \)).
Therefore, the correct response is: subtraction and division.