help needed

[juless]

A teacher wishes to schedule a quiz or exam during part of a two-hour class. The equation l+e=20 can be used to find the available lecture time "l" given that "e" minutes are planned for the quiz or exam. Determine the ordered pairs that satisfy the equation if the domain is (20, 30, 45, 60).

Please help who understands this

 

[Gene]

You have a typo.
i+e=120
i=120-e
Plug in the domain numbers as e and solve for i
The pairs are (e,i)