Write the Word or Phrase That Best Completes Each Statement $$\text { Consider the function } z = \{ ( 9 , - 5 ) , ( - 7,3 ) , ( - 1,9 ) \} \text {. Find the function value } z ( - 7 ) \text {. }$$

Write the word or phrase that best completes each statement or answers the question.
- $$\text { Consider the function } z = \{ ( 9 , - 5 ) , ( - 7,3 ) , ( - 1,9 ) \} \text {. Find the function value } z ( - 7 ) \text {. }$$