Free points I’m hella bored

What is the average rate of change for this function for the interval from x=2 to x=4 ?

Measures of the angle of r, 31 s (x+4) t (3x+9)

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.