To find out how much sugar Ms. Johnson used, we need to calculate half of the sugar in the canister.
We start with the amount of sugar in the canister: \(\frac{7}{8}\) cups.
Now, to find \(\frac{1}{2}\) of \(\frac{7}{8}\), we multiply the two fractions:
\[ \frac{1}{2} \times \frac{7}{8} = \frac{1 \times 7}{2 \times 8} = \frac{7}{16} \]
So, Ms. Johnson used \(\frac{7}{16}\) cups of sugar for the dessert.