When a=4.5, b=2.5, 2a+3b=how much.
当a=4.5，b=2.5时，2a+3b=多少．
<gadget id="calculator">2 * 4.5</gadget>
<output>9</output>

<gadget id="calculator">3 * 2.5</gadget>
<output>7.5</output>

<gadget id="calculator">9 + 7.5</gadget>
<output>16.5</output>

<result>16.5</result>