The school bought 6 desks and several chairs, which cost 770.4 yuan in total, and each desk was 52.4 yuan, which was 23.9 yuan more expensive than each chair. How many chairs did you buy?
学校买来6张书桌和几把椅子，共用770.4元，每张桌子52.4元，比每把椅子贵23.9元，买几把椅子？
<gadget id="calculator">52.4 * 6</gadget>
<output>314.4</output>

<gadget id="calculator">770.4 - 314.4</gadget>
<output>456</output>

<gadget id="calculator">52.4 - 23.9</gadget>
<output>28.5</output>

<gadget id="calculator">456 / 28.5</gadget>
<output>16</output>

<result>16</result>