What is the solution set of x 5

The union of two sets is defined as all elements that are members of both sets.

The first set evaluuates to ( ..., ..., ... - 7,-6,-5,-4) and the second eveluates to (6,7,8,9, ..., ...).

There are no elements that belong to both sets so the solution is the empty set. {∅}

Another way is to think about it in words: "What number (s) are less than - 3 and also greater than 5?" There are no numbers that fit both of these.