Use a cup to fill a kettle with water. After pouring 3 cups of water, the weight of the kettle is 0.85 kg. If the kettle is filled with 5 cups of water, the weight of the kettle is 1.25 kg. How many kilograms does each glass of water weigh?
用一只杯子盛满水向一个水壶里灌水，倒进3杯水后，连水壶共重0.85千克；如果灌满水壶要倒进5杯水，这时连水壶共重1.25千克．每杯水重多少千克？
<gadget id="calculator">1.25 - 0.85</gadget>
<output>0.4</output>

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

<gadget id="calculator">0.4 / 2</gadget>
<output>0.2</output>

<result>0.2</result>