When a=4, b=2.5, how much is 6.2a-2b=.
当a=4，b=2.5时，6.2a-2b=多少．
<gadget id="calculator">6.2 * 4</gadget>
<output>24.8</output>

<gadget id="calculator">2 * 2.5</gadget>
<output>5</output>

<gadget id="calculator">24.8 - 5</gadget>
<output>19.8</output>

<result>19.8</result>