A top is 45 yuan, and the price of a pair of trousers is 20% cheaper than the top. How much does it cost to buy 120 sets of these clothes?
一件上衣45元，一条裤子的价格比上衣便宜20%，购买120套这样的衣服一共要用多少钱？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">45 * (4/5)</gadget>
<output>36</output>

<gadget id="calculator">45 + 36</gadget>
<output>81</output>

<gadget id="calculator">81 * 120</gadget>
<output>9_720</output>

<result>9_720</result>