When x=how much, (35-5x)*4=0.
当x=多少时，(35-5x)*4=0．
<gadget id="calculator">35 * 4</gadget>
<output>140</output>

<gadget id="calculator">140 - 0</gadget>
<output>140</output>

<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">140 / 20</gadget>
<output>7</output>

<result>7</result>