If a piece of wood is sawed into 5 sections, the sawing fee is 4 yuan. 6 pieces of wood are sawed into 4 sections, how much is the sawing fee?
一根木头锯成5段要付锯板费4元．6根木头，每根锯成4段，共要付锯板费多少元？
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

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

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

<gadget id="calculator">1 * 3 * 6</gadget>
<output>18</output>

<result>18</result>