The set $A$ is defined as $A = \{ 5, 6, 9, 10 \}$.

Since this is a subset of the universal set $U = \{ 4, 5, 6, 7, 8, 9, 10 \}$, we can confirm that each element in set $A$ is also present in $U$.

Would you like to explore more about set theory, or do you have specific questions about this set?

Here are some related questions to consider:

1. What is the complement of set $A$ in $U$?
2. How do you find the union of sets $A$ and $B$ if $B$ is given?
3. What is the intersection of sets $A$ and $B$ if $B$ is given?
4. How do you determine if one set is a proper subset of another?
5. How can you represent these sets using a Venn diagram?

Tip: When working with sets, it's helpful to visualize them using Venn diagrams to better understand the relationships between them.