Put 10 grams of salt in a glass of water, and then add 20 grams of 5% brine to make 4% brine. Question: How many grams of water is there in this glass of water?
一杯水中放入10克盐，再加入浓度5%的盐水20克，配制成浓度为4%的盐水．问：原来这杯水中有水多少克？
<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">20 * (1/20)</gadget>
<output>1</output>

<gadget id="calculator">10 + 1</gadget>
<output>11</output>

<gadget id="calculator">4 / 100</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">11 / (1/25)</gadget>
<output>275</output>

<gadget id="calculator">275 - 10 - 20</gadget>
<output>245</output>

<result>245</result>