15的英語單詞怎麼寫

例句：

In those days most people left school when they were only fifteen years old.

那時候，大多數人上學只上到十五歲。

The wiring in your house should be renewed every ten to fifteen years.

你家裏的電線應該每十到十五年更新一次。

The room measures fifteen feet by twenty feet.

房間15英尺寬20英尺長。