Mix 30% salt water and 40% salt water together to make 34% salt water, but accidentally reverse the ratio. So what is the concentration of the wrong brine?
把浓度为30%的盐水和40%的盐水混在一起，想配成浓度为34%的盐水，可是不小心把比例弄反了．那么配错了的盐水浓度是多少？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">2 * (3/10)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 * (2/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(3/5) + (6/5)</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">(9/5) / 5</gadget>
<output>9/25 = around 0.36</output>

<result>9/25 = around 0.36</result>