The school held a math contest with 20 questions. He got 5 points for doing a correct question, and deducted 3 points for not doing a question or doing a wrong one. Liu Hao scored 60 points. How much did he do right?
1. Assuming everything is correct, you will get 20×5= 100 points, so you will get 100-60=40 points; Answering a question correctly is 5+3=8 points more than answering a question incorrectly, that is to say, the wrong question is 40÷8=5, and then the right question is 20-5= 15.
20-(20×5 - 60)÷(5+3)
=20 - 40÷8
=20 - 5
= 15 (road)
2. Solution: Suppose he did the X problem correctly.
5x-3 (20x) =60
The solution is x= 15.
A: He got it right 15.