A store bought a batch of New Year's cards at a price of 2.1 cents each, and sold them for a total of 14.57 yuan. If the selling price of each sheet is the same and does not exceed twice the purchase price, how much is the store's profit?
一商店一每张2角1分的价格进了一批贺年卡，共卖了14.57元．若每张的售价相同，且不超过买入价格的两倍，则商店赚了多少角．
<gadget id="calculator">31 - 21</gadget>
<output>10</output>

<gadget id="calculator">47 / 10</gadget>
<output>47/10 = around 4.7</output>

<gadget id="calculator">10 * (47/10)</gadget>
<output>47</output>

<result>47</result>