当たり

The word 当たり can be added to a counter as a suffix to give a "per" type meaning. The structure used is often one of the following:

Number + Counter 当たり Number + Counter
Example: 1時間当たり10ドル = $10 per hour

Number + Counter 当たりの Noun
Example: 一人当たりのコスト = Cost per person

夏休みに1か月アルバイトをして15万円もらった。1日当たり5千円もらったことになる。
During summer break I worked a part time job for a month and made 150,000 yen. That ends up being 5,000 yen per day.

子供が10人います。みかんは30個ありますから、一人当たり何個食べられますか？
There are ten kids. Since there are 30 oranges, how many can each kid eat?

This is a difficult lesson to do examples for because I don't know counters well at all, so I'll have to do some more reading on them.