1800/((15+□)*3)=24, what is the number to be filled in □.
1800/((15+□)*3)=24，□里要填的数是多少．
<gadget id="calculator">1_800 / 24 / 3</gadget>
<output>25</output>

<gadget id="calculator">25 - 15</gadget>
<output>10</output>

<result>10</result>