7 years ago, the age of the older sister was 4 times that of the younger sister. Seven years later, the combined age of the two sisters was 48 years old. How old is your sister?
7年前，姐姐的年龄是妹妹的4倍，7年后姐妹俩的年龄和是48岁．姐姐今年多少岁？
<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<gadget id="calculator">48 - 14 - 14</gadget>
<output>20</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">16 + 7</gadget>
<output>23</output>

<result>23</result>