The school has 28 basketballs, twice the number of footballs, and 15 more volleyballs than the total number of basketballs and footballs. How many volleyballs are there?
学校有篮球28个，足球的个数是篮球的2倍，排球比篮球和足球的总数多15个．排球有多少个？
<gadget id="calculator">28 * 2</gadget>
<output>56</output>

<gadget id="calculator">56 + 28</gadget>
<output>84</output>

<gadget id="calculator">84 + 15</gadget>
<output>99</output>

<result>99</result>