A piece of trapezoidal glass, with an upper base of 90 cm, a lower base of 160 cm, and a height of 80 cm, costs 45 yuan per square meter of glass. How much does it cost to buy 20 pieces of such glass?
一块梯形玻璃，上底90厘米，下底160厘米，高80厘米，每平方米玻璃45元，买这样的玻璃20块，共需多少钱？
<gadget id="calculator">90 + 160</gadget>
<output>250</output>

<gadget id="calculator">80 / 2</gadget>
<output>40</output>

<gadget id="calculator">20 / 10_000</gadget>
<output>1/500 = around 0.002</output>

<gadget id="calculator">250 * 40 * (1/500) * 45</gadget>
<output>900</output>

<result>900</result>