To find the fraction of the assignment that Celeste's mom checked, we can multiply the fraction of the problems Celeste completed (5/6) by the fraction of those that her mom checked (2/3).
Here’s the calculation:
\[ \text{Fraction checked} = \left( \frac{5}{6} \right) \times \left( \frac{2}{3} \right) \]
Multiply the numerators and the denominators:
\[ = \frac{5 \times 2}{6 \times 3} = \frac{10}{18} \]
Now simplify \(\frac{10}{18}\):
\[ = \frac{5}{9} \]
So, the fraction of the assignment that Celeste's mom checked is \(\frac{5}{9}\).
The correct answer is:
5/9