The elder brother has 28 yuan, and after giving the younger sister 4.6 yuan, the two have the same amount of money. How much is the younger sister's original money?
哥有28元钱，给了妹4.6元后两人的钱一样多，妹妹原有多少元钱．
<gadget id="calculator">2 * 4.6</gadget>
<output>9.2</output>

<gadget id="calculator">28 - 9.2</gadget>
<output>18.8</output>

<result>18.8</result>