To determine how many stickers Reann started with, let's denote the number of stickers she started with as \( x \).
- Reann gives her friend half of her stickers: This means she gives away \( \frac{x}{2} \), so she now has \( x - \frac{x}{2} = \frac{x}{2} \).
- Then her brother gives her 8 stickers: Now she has \( \frac{x}{2} + 8 \).
- We know that she ends up with 12 stickers:
\[ \frac{x}{2} + 8 = 12 \]
To solve for \( x \):
- First, we subtract 8 from both sides:
\[ \frac{x}{2} = 12 - 8 \] \[ \frac{x}{2} = 4 \]
- Then, we multiply both sides by 2 to solve for \( x \):
\[ x = 4 \times 2 \] \[ x = 8 \]
In summary, the operations needed to solve this problem are:
- Division (to find half of her stickers).
- Addition (to add the stickers her brother gives her, and to set up the equation with the total).
Thus, the correct answer is B. addition and division.