Math Question problem

Question

the aplicant earns 5 points for each correct answer and loses one point for each incorrect answered all 30 questions with a score of 120 how many question did he have correct

Answer 1

I set this up as a system of linear equations w is the number correct y is the number incorrect which gives me

x+y=30 and 5x-1y=120 you can solve using any of the methods substitution, graphing, elimination, matrix. I solved using matrix and got 25 qustions correct and 5 answers incorrect. To check 25*5=125 and 5*-1=-5 125-5=120