This year, the combined age of the two sisters is 55 years old. A few years ago, when the elder sister was only as old as the younger sister is now, the younger sister's age was exactly half of the elder sister's age. How old is your sister this year?
今年，姐妹俩年龄的和是55岁，若干年前，当姐姐的年龄只有妹妹现在这么大时，妹妹的年龄恰好是姐姐年龄的一半．姐姐今年是多少岁？
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">55 / 5</gadget>
<output>11</output>

<gadget id="calculator">3 * 11</gadget>
<output>33</output>

<result>33</result>