Jane is taking a class and asks you to help her figure out what her last grade must be in the class to get a 85 in the class. She tells you the following calculation is used to find your final grade:

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x is her last score which has not been taken. Explain this equation and the process you would use to solve for the unknown test score. Solve for the test score.

** could you please elaborate on how you came to the conclusion of the answer?

Thank you!