Teacher Wang bought back a batch of balls, among which the number of basketballs is 3/4 of that of footballs, the number of footballs is 2/3 of that of volleyballs, there are 15 basketballs, how many volleyballs are there?
王老师买回一批球，其中篮球的个数是足球的(3/4)，足球的个数是排球的(2/3)，篮球有15个，排球有多少个？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">15 / (3/4) / (2/3)</gadget>
<output>30</output>

<result>30</result>