When m=3, n=2, how much is 2.5m-1.5=.
当m=3，n=2时，2.5m-1.5=多少．
<gadget id="calculator">2.5 * 3</gadget>
<output>7.5</output>

<gadget id="calculator">7.5 - 1.5</gadget>
<output>6</output>

<result>6</result>