Final answer:
We cannot accurately infer why Emma's method worked in calculating the cost of Chet's flight as the context does not provide enough information.
Step-by-step explanation:
The question pertains to solving a mathematical equation. It seems there are some typographical errors, and the context provided does not explain Emma's method or give any insight into the calculation that resulted in Chet's flight costing $18399. Therefore, the accurate answer would be D) Emma's method is not explained in the text.
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