This topic mainly investigates the application of the idea of average sum equation.

Equation method

Solution:

We can assume that we have taken X exams before,

Then the previous total score is 9 1.5x, and this total score is 9 1.5x+99.

According to the meaning of the question, after this exam, the average score was 92 points, ***(x+ 1) times.

Now the total score can also be expressed as 92(x+ 1).

So you can list 9 1.5x+99=92(x+ 1).

The solution is x= 14, so this is the exam x+ 1= 15.