There are 40 grams of water in 50 grams of salt water, how much salt accounts for the salt water.
50克盐水中有水40克，盐占盐水的多少．
<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<gadget id="calculator">10 / 50</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>