For the health and safety of the students, the school provides each student with a water cup. Each water cup is 3 yuan, which happens to be a 10% discount in the supermarket. The school wants to buy 180 water cups. Please calculate how much it will cost in total?
为了学生的卫生安全，学校给每个学生配一个水杯，每只水杯3元，正好超市打九折，学校想买180只水杯，请你算一下一共需要多少钱？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">3 * (9/10) * 180</gadget>
<output>486</output>

<result>486</result>