The precipitation in a certain area in the previous year was 540 millimeters, and the precipitation in last year was 25% less than that in the previous year. How many millimeters was the precipitation in this area last year?
某地区前年降水量是540毫米，去年降水量比前年少25%，这个地区去年降水量是多少毫米？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">540 * (3/4)</gadget>
<output>405</output>

<result>405</result>