The elder sister was twice as old as the younger sister four years ago, and 1.5 times the younger sister's age this year. Ask my sister's age this year?
姐姐四年前的年龄是妹妹年龄的2倍，今年的年龄是妹妹年龄的1.5倍．问姐姐今年的年龄？
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">8 - 4</gadget>
<output>4</output>

<gadget id="calculator">2 - 1.5</gadget>
<output>0.5</output>

<gadget id="calculator">4 / 0.5</gadget>
<output>8</output>

<gadget id="calculator">8 * 1.5</gadget>
<output>12</output>

<result>12</result>