The elder brother gave half of the stamps in his collection to his younger brother, and he has 30 stamps left. How many stamps did the older brother have?
哥哥把收藏的一半邮票送给弟弟，自己还剩30枚，哥哥原来有多少枚邮票？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">30 / (1/2)</gadget>
<output>60</output>

<result>60</result>