80 kg is reduced by how much is 50 kg.
80千克减少多少是50千克．
<gadget id="calculator">80 - 50</gadget>
<output>30</output>

<gadget id="calculator">30 / 80</gadget>
<output>3/8 = around 0.375</output>

<result>3/8 = around 0.375</result>