It is known that the arithmetic sequence 2, 5, 8, 11, 14..., ask what is the number 47 in it.
已知等差数列2，5，8，11，14…，问47是其中第多少项．
<gadget id="calculator">47 - 2</gadget>
<output>45</output>

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">45 / 3</gadget>
<output>15</output>

<gadget id="calculator">15 + 1</gadget>
<output>16</output>

<result>16</result>