Please help me due at tomorrow 8a. m

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

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.

Solve 2x2 + 8 = 0 by graphing the related function. there are two solutions: . there are no real number solutions. there are two solutions: 2 and -2