The sum of 2 times x plus x is 18, find x, the correct solution is x=
x的2倍加上x的和是18，求x，正确的解是x=多少
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">18 / 3</gadget>
<output>6</output>

<result>6</result>