It costs 40 yuan to buy a basketball, which is 15 yuan more expensive than buying a football. The money Mr. Li brought was just enough to buy 10 basketballs. If you use this money to buy footballs, how many can you buy?
买一个篮球要40元，比买一个足球贵15元．李老师带的钱刚好能买10个篮球．如果用这些钱买足球，可以买多少个？
<gadget id="calculator">40 - 15</gadget>
<output>25</output>

<gadget id="calculator">10 / 25</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">40 * (2/5)</gadget>
<output>16</output>

<result>16</result>