piece of wood with uniform thickness is 20 decimeters long, and it needs to be sawn into sticks with a length of 4 decimeters. It takes 3 minutes to saw each time, and 2 minutes to rest after sawing a section. How many minutes will it take to saw all the pieces?
一根粗细均匀的木头长20分米，要锯成4分米长的木棍，每锯一次要3分钟，锯完一段休息2分钟，全部锯完要用多少分钟？
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">12 + 6</gadget>
<output>18</output>

<result>18</result>