The sports team of Yuhong Elementary School bought some basketballs and footballs for 720 yuan. It is known that one basketball is 20 yuan more expensive than one football, and the price of 3 basketballs and 4 footballs is equal. If you buy footballs, how many can you buy?
育红小学体育组花了720元买了一些篮球和足球，已知一个篮球比一个足球贵20元，并且3个篮球和4个足球的价格相等，如果都买足球，可以买多少个？
<gadget id="calculator">4 * 20</gadget>
<output>80</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<gadget id="calculator">80 / 1</gadget>
<output>80</output>

<gadget id="calculator">80 - 20</gadget>
<output>60</output>

<gadget id="calculator">720 / 60</gadget>
<output>12</output>

<result>12</result>