In the past three months, the school's electricity consumption has risen sharply. The electricity consumption in April was 100 kWh more than that in March, and in May was 400 kWh more than in April, and the electricity consumption in May was 1.5 times that in April. How many kilowatt-hours of electricity are used in April?
最近三个月，学校用电量大幅上升．四月份比三月份多用电100千瓦时，五月份比四月份多用400千瓦时，五月份用电量是四月份的1.5倍．求四月份用电多少千瓦时？
<gadget id="calculator">1.5 - 1</gadget>
<output>0.5</output>

<gadget id="calculator">400 / 0.5</gadget>
<output>800</output>

<result>800</result>