HELP PLEASE!!! A railroad's track can be determined using the following graph. Several different roadways are in the same region as the railroad. Part A: A highway's path can be found using the equation 2x + 3y = 21. Use the graphs of the functions to determine the number of intersections there will be between the railroad and the highway, and explain completely.

Part B: A turnpike's route is determined by the equation y equals one third times x squared period Prove algebraically how many intersections there will be between the railroad and the turnpike, showing all necessary work.