Question

create 2 sets that have a union (-1,0,1,2,3,4,5,6)

Answer 1

@triciaal

Answer 2

Here are two sets that have a union of { 1, 2, 3, 4 }:
{ 1, 2 } and { 3, 4 }

Do you think you can do something similar with your set? :)

Answer 3

look at the example above.
the given set is separated into 2 sets all the elements are accounted for
the number of elements in each set does not have to be the same.