□*2.5-1.3=5.7, what is the number in □.
□*2.5-1.3=5.7，□中的数是多少．
<gadget id="calculator">5.7 + 1.3</gadget>
<output>7</output>

<gadget id="calculator">7 / 2.5</gadget>
<output>2.8</output>

<result>2.8</result>