There is a pile of cement. There are 24 bags on the upper layer and 30 bags on the bottom layer. There are 7 layers in total. How many bags are there in this pile of cement?
有一堆水泥，上层放24包，最下层放30包，共有7层，这堆水泥共多少包？
<gadget id="calculator">24 + 30</gadget>
<output>54</output>

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

<gadget id="calculator">54 * (7/2)</gadget>
<output>189</output>

<result>189</result>