To find out how much sugar Ms. Johnson used, we need to calculate one half of the 7/8 cups of sugar.
To do this, we multiply \( \frac{7}{8} \) by \( \frac{1}{2} \):
\[ \frac{7}{8} \times \frac{1}{2} = \frac{7 \times 1}{8 \times 2} = \frac{7}{16} \]
So, Ms. Johnson used \( \frac{7}{16} \) cups of sugar for the dessert.