Mengmeng is studying and uses 15-watt energy-saving lamps. The electricity bill for one month (30 days) costs 0.324 yuan. How many hours does Mengmeng study every night? (Electricity fee is 0.48 yuan per kilowatt-hour)
蒙蒙在学习，用的是15瓦的节能灯，一个月(30天)的电费要用0.324元，蒙蒙每天晚上的学习时间是多少小时？(每千瓦时即每度电费0.48元)
<gadget id="calculator">0.324 / 30 / 0.48</gadget>
<output>0.0225</output>

<gadget id="calculator">1_000 / 15</gadget>
<output>200/3 = around 66.666667</output>

<gadget id="calculator">0.0225 * (200/3)</gadget>
<output>1.5</output>

<result>1.5</result>