The pocket money saved by the elder brother is 20 yuan less than that of the younger sister, and 10 yuan more than twice that of the younger brother. Who saves more pocket money? How much?
哥哥存的零花钱比妹妹的2倍少20元，比弟弟的2倍多10元，弟弟和妹妹谁存的零花钱多？多多少？
<gadget id="calculator">20 + 10</gadget>
<output>30</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<result>15</result>