Because they are all integrated, 53+29+28=74 (people)

Three people did ***9 questions altogether.

74-9=65

If all 65 questions are answered by one person to the question of 1, it should be 65 people.

But 53-3=50

So the number of people who answered these two questions correctly is 65-50= 15.

The rest are 35 people who did the right thing.

If the latter is not clear, you can make a set of equations. If you have a junior high school level, you can make a list. I won't make a list. It's too simple. Take it out, too.

Give points.