More minor page count tweaks & fixes

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oreilly/workflow-basics.html

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 Exercises</h1>
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 Summary</h1>
 <p>Now that you’ve learned a little more about how R code works, and some tips to help you understand your code when you come back to it in the future. In the next chapter, we’ll continue your data science journey by teaching you about dplyr, the tidyverse package that helps you transform data, whether it’s selecting important variables, filtering down to rows of interest, or computing summary statistics.</p>