A certain supermarket mineral water promotion, buy 5 get 1 free. There are 90 students visiting the park. Each of them wants to drink a bottle of mineral water. How much does they need to pay for the bottle of mineral water?
某超市矿泉水搞促销活动，买5送1．有90名学生游园，他们每人想喝一瓶矿泉水，只需要付多少瓶的矿泉水的钱？
<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<gadget id="calculator">90 / 6</gadget>
<output>15</output>

<gadget id="calculator">15 * 5</gadget>
<output>75</output>

<result>75</result>