If 100 Australian dollars can be exchanged for 55 US dollars. An Australian tourist bought an item worth $100 in a store in the United States. But he paid 200 Australian dollars, so how much should the store's opening ceremony give him?
假若100澳元可兑换55美元．一位澳洲游客在美国一家店铺买了一个价值100美元的物品．但是他付了200澳元，那么店铺的营业贺应该找给他多少美元．
<gadget id="calculator">200 / 100</gadget>
<output>2</output>

<gadget id="calculator">2 * 55</gadget>
<output>110</output>

<gadget id="calculator">110 - 100</gadget>
<output>10</output>

<result>10</result>