Teacher Wang arrives at school at 7:30 in the morning, leaves work at 11:30 noon, arrives at school at 2:00 pm, and leaves work at 5:30 in the evening. How many hours does Mr. Wang work in school a day?
王老师早上7：30到校，中午11：30下班，下午2：00到校，傍晚5：30下班．王老师在校工作一天的时间是多少小时．
<result>7.5</result>