The school used 450 kWh of electricity in April, saving 10% compared with March. How many kilowatt-hours does the school use in March?
学校四月份用电450千瓦时，比三月份节约10%．学校三月份用电多少千瓦时？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">450 / (9/10)</gadget>
<output>500</output>

<result>500</result>