The school bought 36 footballs in September, which was twice the number of footballs purchased in October. The two times spent a total of 1539 yuan. How much is an average football?
学校9月份买了36个足球，是10月份购买足球个数的2倍，两次一共花了1539元．平均每个足球多少元？
<gadget id="calculator">36 / 2</gadget>
<output>18</output>

<gadget id="calculator">18 + 36</gadget>
<output>54</output>

<gadget id="calculator">1_539 / 54</gadget>
<output>57/2 = around 28.5</output>

<result>57/2 = around 28.5</result>