Xiao Ming did more homework at 6 p.m. and found that the finished homework on the clock was that the angle between the hour hand and the minute hand of the clock was 120 degrees. At this time, it was nearly 7 p.m. and Xiao Ming spent several hours doing homework

Xiao Ming did more homework at 6 p.m. and found that the finished homework on the clock was that the angle between the hour hand and the minute hand of the clock was 120 degrees. At this time, it was nearly 7 p.m. and Xiao Ming spent several hours doing homework

480 out of 11

Do your homework between 8:00 and 9:00. The hour hand and the minute hand on the clock face are on the same line. When you finish a set of questions, the hour hand and the minute hand coincide. Then it takes () minutes to do the questions

Doing homework between 8:00 and 9:00, the hour and minute are in a straight line, which means before 8:15
Let this be 8 o'clock x-score
(15-x)/5=x/60
x=13.35
When you finish your homework, it will be ten minutes
Let this be 8 o'clock y-score
(y-40)/5=y/60
=43.64
So the question is Y-X = 43.64-13.35
=30.29 (min)

Xiaoming Chong began to do his homework at 3 p.m. when he finished his homework, the hour hand and minute hand coincided for the first time. How long did it take Xiaoming to do his homework?

21 points