The school bought 30 basketballs and 16 footballs. The number of badmintons bought is three times the difference between the number of basketballs and footballs. How many badmintons do you buy?
学校买来篮球30个，足球16个．买羽毛球的个数是篮球与足球个数差的3倍．买羽毛球多少个？
<gadget id="calculator">30 - 16</gadget>
<output>14</output>

<gadget id="calculator">14 * 3</gadget>
<output>42</output>

<result>42</result>