When x=3, a=4, b=2, what is the formula 4x-2a/b=
当x=3，a=4，b=2时，式子4x-2a/b=多少
<gadget id="calculator">4 * 3</gadget>
<output>12</output>

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

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

<gadget id="calculator">12 - 4</gadget>
<output>8</output>

<result>8</result>