The price of a set of desks and chairs is 108 yuan. It is known that the price ratio of chairs to desks is 2:7. How much is the price of the chairs? (Answer with two different knowledge).
一套课桌椅的价钱是108元，已知椅子与课桌价钱的比是2：7，椅子的价钱是多少元？(用两种不同的知识解答)．
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 + (2/7)</gadget>
<output>9/7 = around 1.285714</output>

<gadget id="calculator">108 / (9/7)</gadget>
<output>84</output>

<gadget id="calculator">84 * (2/7)</gadget>
<output>24</output>

<result>24</result>