The school bought 18 desks and 36 chairs for a total of 3420 yuan. It is known that the price of one desk is equivalent to the price of 3 chairs. How much is a chair?
学校买来18张课桌和36把椅子，共用去3420元，已知一张课桌的价格相当于3把椅子的价格．求一把椅子多少元？
<gadget id="calculator">18 * 3</gadget>
<output>54</output>

<gadget id="calculator">54 + 36</gadget>
<output>90</output>

<gadget id="calculator">3_420 / 90</gadget>
<output>38</output>

<result>38</result>