I would get a more basic book with the concepts covered in the Word Translations. It is probably the most advanced book in the MGMAT set.
You have a few options (you can skip it entirely for now and come back to it later so you are not wasting too much time.
Or you can tackle it with additional prep. Try foundations of GMAT Math
, the 2nd edition just came out a few days ago.
You can also try a high school math book or Kaplan Math Workbook
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