There are some brines with a concentration of 30%. After adding a certain amount of brine with a concentration of 50%, the concentration will increase to 35%. If the same mass of brine with a concentration of 50% is added, how much will the concentration increase?
有浓度为30%的盐水若干，添加入一定数量的浓度为50%的盐水后，浓度增加为35%；如果再添加入相同质量的浓度为50%的盐水后，则浓度增加为多少？
<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

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

<gadget id="calculator">(7/20) - (3/10)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) - (7/20)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(1/20) / (3/20)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 + (1/3)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">(4/3) * (7/20)</gadget>
<output>7/15 = around 0.466667</output>

<gadget id="calculator">(1/2) * (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(7/15) + (1/6)</gadget>
<output>19/30 = around 0.633333</output>

<gadget id="calculator">1 + (1/3) + (1/3)</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">(19/30) / (5/3)</gadget>
<output>19/50 = around 0.38</output>

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

<gadget id="calculator">(19/50) * 1</gadget>
<output>19/50 = around 0.38</output>

<result>19/50 = around 0.38</result>