There are two boxes of chalk, there are 72 in box A and 48 in box B, how many pieces are taken from box A and put into box B to make the chalks in the two boxes equal.
有两盒粉笔，甲盒中有72支，乙盒中有48支，从甲盒中拿出多少支放入乙盒，才能使两盒中的粉笔相等．
<gadget id="calculator">72 + 48</gadget>
<output>120</output>

<gadget id="calculator">120 / 2</gadget>
<output>60</output>

<gadget id="calculator">72 - 60</gadget>
<output>12</output>

<result>12</result>