store spent 425 yuan on water and electricity this month, and the water and electricity bill this month was 15% lower than last month. How much was the water and electricity bill last month?
某商店本月支出水电费425元，本月的水电费比上月节约了15%，上月支出水电费多少元？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 - (3/20)</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">425 / (17/20)</gadget>
<output>500</output>

<result>500</result>