For which sets of values is y a function of x

Need help before 10:05

Add the two expressions 3.8b - 7 and 2.9b + 9 enter your answer in simplified form

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.

Ineed to know the answer to this algebra question.