There is a cup filled with 15% salt water. There are large, medium and small iron balls. Their volume ratio is 10:5:3. First, put the ball deep into the salt water cup. As a result, the salt water overflows by 10%. Take it out The small ball, then sink the middle ball into the saline cup and take it out again, then sink the big ball into the saline cup and take it out, and finally pour pure water into the cup until the cup is full. What is the concentration of salt water in the glass at this time?
有一杯子装满了浓度为15%的盐水，有大、中、小铁球各一个，它们的体积比为10：5：3，首先将小球深入盐水杯中，结果盐水溢出10%，取出小球，其次把中球沉入盐水杯中，又将它取出，接着将大球沉入盐水杯中后取出，最后在杯中倒入纯水至杯满为止．此时杯中盐水的浓度是多少？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

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

<gadget id="calculator">(1/10) / 3</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) * 10</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) / 1</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(3/20) * (2/3)</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>