A math contest was held in Beijing Road Primary School. A total of 20 questions 10, 5 points will be deducted for each question. Wang Leyan's score is 1 10. How many questions did he answer correctly?
Solution: If he answers X correctly, he answers 20-x wrong.
10x-(20-x)×5 = 1 10
10x- 100+5x = 1 10
10x+5x = 1 10+ 100
x=2 10÷ 15
x= 14