Final answer:
The most effective way to combine sentences 8 and 9 is 'A feature of Poor Richard's was advice about how to be happy and successful.'
Step-by-step explanation:
The most effective way to combine sentences 8 and 9 is: A feature of Poor Richard's was advice about how to be happy and successful. This combines the ideas of being happy and successful into a single concise sentence, while maintaining the original meaning of the passage. The other options either change the meaning or make the sentence unnecessarily complicated.
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