The sum of 3 consecutive odd numbers is 39, what is the largest odd number among them?
3个连续奇数的和是39，其中最大的奇数是多少．
<gadget id="calculator">39 / 3</gadget>
<output>13</output>

<gadget id="calculator">13 + 2</gadget>
<output>15</output>

<result>15</result>