fifteen

十五

Add seven and eight and you get fifteen.

七加八等於十五。

十五歲

She started learning the violin at fifteen.

她十五歲開始學小提琴。

十五個、十五人

Out of the fifteen, only three finished the race.

十五個人當中只有三個跑完全程。

十五的、十五個

The meeting lasted fifteen minutes and ended without a decision.

會議開了十五分鐘，最後沒有做出決定。