There are 180 grams of salt water with a concentration of 2% in container A, and several grams of salt water with a concentration of 9% in container B. Take 240 grams of salt water from B and pour it into A. At this time, the amount of salt in both containers A and B equal. How many grams of the original salt water in container B?
甲容器中有浓度为2%的盐水180克，乙容器中有浓度为9%的盐水若干克，从乙中取出240克盐水倒入甲，此时，甲、乙两个容器内的食盐量相等．乙容器中原有盐水多少克．
<gadget id="calculator">2 / 100</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">180 * (1/50)</gadget>
<output>18/5 = around 3.6</output>

<gadget id="calculator">9 / 100</gadget>
<output>9/100 = around 0.09</output>

<gadget id="calculator">240 * (9/100)</gadget>
<output>108/5 = around 21.6</output>

<gadget id="calculator">(18/5) + (108/5)</gadget>
<output>126/5 = around 25.2</output>

<gadget id="calculator">(126/5) / (9/100)</gadget>
<output>280</output>

<gadget id="calculator">280 + 240</gadget>
<output>520</output>

<result>520</result>