Use a teacup to pour water into an empty water bottle. If 2 cups of water are poured into the water bottle, the weight of the water in the water bottle is 540 grams. If 5 cups of water are poured into the water bottle, the weight of the water in the water bottle The weight of the water bottle is 600 grams, what is the weight of the empty water bottle in grams?
用一只茶杯将水倒入一只空水瓶里，如果2杯水倒入这个水瓶里，这个水瓶的和水的重量是540克，如果5杯水倒入这个水瓶里，这个水瓶的和水的重量是600克，空水瓶的重量是多少克．
<gadget id="calculator">600 - 540</gadget>
<output>60</output>

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">60 / 3</gadget>
<output>20</output>

<gadget id="calculator">2 * 20</gadget>
<output>40</output>

<gadget id="calculator">540 - 40</gadget>
<output>500</output>

<result>500</result>