Use 3 paper strips of the same length to form a 30 cm long paper strip. If each joint overlaps by 3 cm, how many centimeters is each paper strip?
用3张同样长的纸条粘结成一条长30厘米的纸条，如果每个接头处都重叠3厘米，那么每张纸条长多少厘米？
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">30 + 6</gadget>
<output>36</output>

<gadget id="calculator">36 / 3</gadget>
<output>12</output>

<result>12</result>