The price of a desk is 210 yuan, which is three times the price of a chair. How much is a chair? (First list the equations involving the unknown x, and then solve them.)
一张办公桌的价钱是210元，是一把椅子的价钱的3倍，一把椅子多少元？(先列出含有未知数x的等式，再解答．)
<gadget id="calculator">210 / 3</gadget>
<output>70</output>

<result>70</result>