There are 15 soccer balls in the sports room, three times the number of basketballs, and three more volleyballs than twice the number of basketballs. How many volleyballs are there in the sports room?
体育室有足球15个，是篮球个数的3倍，排球个数比篮球的2倍还多3个．体育室有排球多少个？
<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">10 + 3</gadget>
<output>13</output>

<result>13</result>