There are 20 water pipes in the bottom layer of a pile, 8 in the top layer, and 2 pipes in the upper layer than in the bottom layer. How many water pipes are there in total in this pile?
一堆水管最下层有20根，最上层有8根，上比下层少2根，这堆水管一共有多少根．
<gadget id="calculator">20 + 8</gadget>
<output>28</output>

<gadget id="calculator">20 - 8</gadget>
<output>12</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">28 * (7/2)</gadget>
<output>98</output>

<result>98</result>