Xiao Ming did an experiment. He added 4 grams of salt and 6 grams of water to an empty cup. What is the salt content of the salt water at this time?
小明做实验，他在空杯中，加入4克盐和6克水，这时盐水的含盐率是等于多少
<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) * 1</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>