There are 20 footballs in the school, more basketballs than footballs (3/4), and as many basketballs as volleyballs (7/3), how many volleyballs does the school have?
学校有足球20个，篮球比足球多(3/4)，篮球的数量是排球的(7/3)，学校有排球多少个？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 + (3/4)</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">7 / 3</gadget>
<output>7/3 = around 2.333333</output>

<gadget id="calculator">(7/4) / (7/3)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">20 * (3/4)</gadget>
<output>15</output>

<result>15</result>