Which of the following sets of ordered pairs represents a function ? (photo included )

Which expression is equivalent to √ -80?

The tuition costs, c, for a local community college are modeled by c(h) = 250 + 200h, where h represents the number of credit hours taken. the local state university has tuition costs, s, modeled by the function s(h) = 300 + 180h. how many credit hours will a student have to take for the two tuition costs to be equal? round the answer to the nearest tenth of an hour.

If chord ab is congruent to chord cd, then what must be true about ef and eg?