In an ordered pair (x,y), x represents the domain, and y is the range.
Gather up all of the domain, the domain is
{-10, -3, 4, 7, 12}
The range is
{-2, 3, 4, 3, 3} ----> {-2, 3, 4} (the same multiple sets counts as one)
A function can be defined as either one-to-one, or many-to-one BUT NOT one-to-many.
Draw a diagram representing the domain mapping to a range.
Based on the diagram, we have mappings of one-to-one [-10 maps to 2, 4 maps to 4, based on the ordered pair (-10,-2) and (4,4)],
and many-to-one [-3, 7, and 12 maps to 3, based on the ordered pair (-3,3), (7,3), and (12,3)]
Since there are no one-to-many mappings, we can conclude that the set is a function.