I can't figure this one. At a math contest,12 problems were given. Five points were awarded for each correct answer,and two points were deducted for each incorrect answer. Matt's score was 39.How many correct answers did he have.5-2(12-5)=39,5-24+2=39,7=63,9

Answer 1

Let x = the number of problems where he got it right
since the total number of problems is 12,
Let 12-x = the number of problems where he git it wrong

Now, it was said that 5 points are awarded for every correct answer, or
5x

and 2 points are deducted for every wrong answer, or
-2(12-x)

and the total score he got is 39. Thus,
5x - 2(12-x) = 39
solving,
5x - 24 + 2x = 39
7x - 24 = 39
7x = 39 + 24
7x = 63
x = 9 correct answers
12-x = 3 wrong answers

hope this helps~ `u`