According to the meaning of the question, 5x+2y-3y=67.
That is 5x-y=67.
There is a need for reasoning here.
Multiply a number by 5, and the last digit of the result may be 0 or 5.
So it can be inferred that y must be a number ending in 3 or 8.
(Because there are 20 questions, it can only be 3 or 8. )
When y=3, x= 14, 14+3+3=20, it meets the question type.
When y=8, x= 15, 15+8+8=3 1, which does not meet the question.
So, Xiao Ming did the right 14 question, and there were three wrong and wrong answers.