Master Wang is going to make a rectangular wooden door. The length of the door is 10.5 meters, which is 3.5 times the width. How many square meters of wood is needed to make this wooden door?
王师傅要做一个长方形的木门，门长10.5米，是宽的3.5倍，做这个木门需要多少平方米的木料？
<gadget id="calculator">10.5 / 3.5</gadget>
<output>3</output>

<gadget id="calculator">10.5 * 3</gadget>
<output>31.5</output>

<result>31.5</result>