To find the difference between the amount Anna ate and the amount she gave to her brother, you need to subtract the fraction representing the amount she gave from the fraction representing the amount she ate.
Anna ate \( \frac{5}{8} \) of the orange and gave \( \frac{3}{8} \) to her brother. The equation to represent this would be:
\[ \frac{5}{8} - \frac{3}{8} = \frac{2}{8} \]
Thus, the correct response is:
5/8 − 3/8 = 2/8