If the equation ((□+2.28)*1.5-0.15)/2.5=12.18 holds true, then what should be the number filled in □.
如果等式((□+2.28)*1.5-0.15)/2.5=12.18成立，那么□中所填的数应是多少．
<gadget id="calculator">12.18 * 2.5</gadget>
<output>30.45</output>

<gadget id="calculator">30.45 + 0.15</gadget>
<output>30.6</output>

<gadget id="calculator">30.6 / 1.5</gadget>
<output>20.4</output>

<gadget id="calculator">20.4 - 2.28</gadget>
<output>18.12</output>

<result>18.12</result>