When a=0.5, b=4, what is the value of 2a+3b.
当a=0.5，b=4时，2a+3b的值是多少．
<gadget id="calculator">2 * 0.5</gadget>
<output>1</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">1 + 12</gadget>
<output>13</output>

<result>13</result>