The price of a badminton racket is 10 times the price of a shuttlecock. Lin Fang bought a badminton racket and 3 shuttlecocks, which cost a total of 39 yuan. How much does it cost to buy badminton? (solution by equation)
一只羽毛球拍的价钱是一个羽毛球价钱的10倍．林芳买了一只羽毛球拍和3个羽毛球，一共花了39元．买羽毛球花的钱是多少元？(用方程解)
<gadget id="calculator">3 + 10</gadget>
<output>13</output>

<gadget id="calculator">39 / 13</gadget>
<output>3</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<result>9</result>