A pile of wood is piled up in a pile (the cross section is trapezoidal shape), there are 2 logs in the upper layer, 6 logs in the lower layer, and a total of 5 layers. How many logs are there in total in this pile.
一堆木料堆成一堆(横截面是梯形形状)，上层有2根，下层有6根，共有5层，这堆木料一共有多少根．
<gadget id="calculator">2 + 6</gadget>
<output>8</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">8 * (5/2)</gadget>
<output>20</output>

<result>20</result>