From the graph, it is clear that the graph is heading towards positive infinity from x=-4.
The point x=-4 is included in the graph as the starting point of the graph i.e. x=4 is showing a closed circle on x=4, and heading towards positive infinity onward.
You multiply 42.75 x 4 and get 171. Then you add 171+52.45=223.45 and then you subtract 223.45-18=205.45 and then you multiply 223.45 x .3333 = 68.3265 or 68.33 (rounded)