Assuming everything is right, the score is 10× 10= 100. A wrong line is equal to 10+20=30 points, so the number of wrong questions is (100-40)÷30=2 questions.

So Xiao Ming was wrong by two and right by eight.

Through extra analysis, Xiao Ming answered 8 questions correctly, which should be 80 points. Why 40 points?

Think about it first. If you answered 8 questions correctly, you must have missed 2 questions. One question is 20 points, so two questions are 2×

20=40 points. Deduct 40 points from the original 80 points, so it is 80 points.

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