Put a bunch of apples into some baskets. If you put 12 apples in each basket, there will be 3 more apples. If you put 13 apples in each basket, 4 apples will be missing. How many apples are there in this pile?
将一堆苹果放进一些筐里，每筐放12个，则多出3个苹果放不下，每筐放13个，又缺4个苹果，这堆苹果有多少个．
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">13 - 12</gadget>
<output>1</output>

<gadget id="calculator">7 / 1</gadget>
<output>7</output>

<gadget id="calculator">12 * 7</gadget>
<output>84</output>

<gadget id="calculator">84 + 3</gadget>
<output>87</output>

<result>87</result>