100 grams of 20% salt water and 150 grams of 30% salt water are mixed together. After pouring out 100 grams of them, add 100 grams of water. What is the concentration of the salt water at this time?
20%的盐水100克和30%的盐水150克混合在一起，倒掉其中的100克后，再加入100克水，这时盐水的浓度是多少？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">100 * (1/5)</gadget>
<output>20</output>

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

<gadget id="calculator">150 * (3/10)</gadget>
<output>45</output>

<gadget id="calculator">20 + 45</gadget>
<output>65</output>

<gadget id="calculator">100 + 150</gadget>
<output>250</output>

<gadget id="calculator">100 / 250</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">250 - 100</gadget>
<output>150</output>

<gadget id="calculator">150 + 100</gadget>
<output>250</output>

<gadget id="calculator">(3/5) / 250</gadget>
<output>3/1_250 = around 0.0024</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">65 * (3/1_250) * 1</gadget>
<output>39/250 = around 0.156</output>

<result>39/250 = around 0.156</result>