It really depends on what kind of problem. like if you are doing a word problem or whatever than you should read the question a couple times, underline key words, DECIDE which operation to use, refer to the question and see if it makes sense. Hope I helped :)
C, because the equation of the table is y=80x. The equation for the graph is y=45x. When x is 11, you have 880 and 495. The difference is 385.
