Initially, there are 18 children at the party:
- 11 children have blankets.
- 7 children have stuffed animals.
Since no children have both, the total number of children remains 18.
When Jorge arrives with a stuffed animal, the situation changes as follows:
- The number of children with stuffed animals goes from 7 to \( 7 + 1 = 8 \).
- The total number of children now becomes \( 18 + 1 = 19 \).
Now, we need to find the fraction of the children at the party that have stuffed animals:
\[ \text{Fraction of children with stuffed animals} = \frac{\text{Number of children with stuffed animals}}{\text{Total number of children}} = \frac{8}{19} \]
Thus, the answer is:
\(\frac{8}{19}\)