The percent of college freshmen who enter college intending to major in a specific subject has increased steadily in recent years. The​ percent, y, who entered college x years after 2003 intending to major in a specific subject is approximated by the following linear equation.
                                               yequals=0.21070.2107xplus+15.7715.77
​a) What interpretation can be given to the​ y-intercept of the graph of the​ equation?
​b) Approximately what percent of college freshmen entering in 20112011 intended to major in a specific​ subject?
​c) In what year did approximately​ 18% of entering college freshmen intend to major in a specific​ subject?