Pls how is the graph of the function on the left different from the graph of the function on the right ?

If you answer 2+2 you will get over 80 points

Aretha wanted to gather data about the cost of local bowling leagues in her area. she plotted the data and determined that the average bowling league costs consist of a one-time registration fee and a monthly fee modeled by the equation y = 15x + 20. identify and interpret the y-intercept in this model. the y-intercept is 20. this is the cost per month. the y-intercept is 20. this is the cost of registration. the y-intercept is 15. this is the cost of registration. the y-intercept is 15. this is the cost per month.

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