When x=15, what is the value of 2x-2*4.
当x=15时，2x-2*4的值是多少．
<gadget id="calculator">2 * 15</gadget>
<output>30</output>

<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">30 - 8</gadget>
<output>22</output>

<result>22</result>