If a dozen people get on a train and five of them get off at the next stop how may of those people are left on the train

Can someone me with this problem . show your work .

For f(x)=2x+3 and g(x)=x^2- 8 find (f+g) (x)

Josh has a rewards card for a movie theater he receives 15 points for becoming a rewards card holder he earns 3.5 points for each visit to the movie theater he needs at least 55 points to earn a free movie ticket which inequality can josh use to determine x, the minimum number of visits he needs to earn his first free movie ticket.