The school bought 4 tables and 9 chairs, which cost 504 yuan. The price of 1 table and 3 chairs is exactly the same. How much is each table?
学校买了4张桌子和9把椅子，共用了504元，1张桌子和3把椅子的价钱正好相等．每张桌子多少元？
<gadget id="calculator">9 / 3</gadget>
<output>3</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<gadget id="calculator">504 / 7</gadget>
<output>72</output>

<result>72</result>