请教OG紫皮-DS-10

[紫皮DS page.149]

10.Of the 230 single-family homes built in city X last year, how many were occupied at the end of the year?

(1) Of all single-family homes in city X,90 percent were occupied at the end of last year.

(2) A total of 7,200 single-family homes in city X were occupied at the end of last year.

Answer: E

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这题不是很理解，烦请哪位帮忙解释一下？非常非常感谢！