There are 16 basketballs in the school, 4 more than footballs. The number of volleyballs is the sum of the number of basketballs and footballs. How many balls are there in total?
学校有16个篮球，比足球多4个，排球的个数是篮球和足球个数的总和，三种球共有多少个？
<gadget id="calculator">16 - 4</gadget>
<output>12</output>

<gadget id="calculator">16 + 12</gadget>
<output>28</output>

<gadget id="calculator">12 + 28 + 16</gadget>
<output>56</output>

<result>56</result>