SOLUTION: Charles took a maths exam with 20 questions. For every correct question, Charles received 10 marks. For every incorrect or unanswered question,he lost 5 marks. If his final score w

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Question 1135003: Charles took a maths exam with 20 questions. For every correct question, Charles received 10 marks. For every incorrect or unanswered question,he lost 5 marks. If his final score was 140 marks, how many questions were answered correctly
Answer by ikleyn(52812) About Me  (Show Source):
You can put this solution on YOUR website!
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            Lovely problem . . . 


Let x = how many questions were answered correctly.


Then the number of questions answered incorrectly is (20-x).


Charles earned 10x marks and lost 5*(20-x) marks.


His balance is


    10x - 5*(20-x) = 140.


Solve it and find the answer to your question.