If 20 kg of salt water with a concentration of 10% is added, how many kg of salt water with a concentration of 30% is added to obtain a salt water with a concentration of 22%.
现有浓度为10%的盐水20千克，再加入多少千克浓度为30%的盐水，可以得到浓度为22%的盐水．
<gadget id="calculator">22 / 100</gadget>
<output>11/50 = around 0.22</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(11/50) - (1/10)</gadget>
<output>3/25 = around 0.12</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/10) - (11/50)</gadget>
<output>2/25 = around 0.08</output>

<gadget id="calculator">(3/25) / (2/25)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">20 * (3/2)</gadget>
<output>30</output>

<result>30</result>