5subtracted from 4 times a number is 27.what is the number?

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.

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.