document.write( "Question 1041651: In an examination, a student scores 5 marks for every correct answer and loses 2 marks for every incorrect answer. A student attempts 75 questions and scores 165 marks. How many questions did he answer correctly? \n" ); document.write( "

Algebra.Com's Answer #656581 by josmiceli(19441) $\"\"$ $\"About$

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Let $\"+n+\"$ = the number of correct answers
\n" ); document.write( " $\"+75+-+n+\"$ = the number of incorrect answers
\n" ); document.write( "------------------------
\n" ); document.write( " $\"+5n+-+2%2A%28+75+-+n+%29+=+165+\"$
\n" ); document.write( " $\"+5n+-+150+%2B+2n+=+165+\"$
\n" ); document.write( " $\"+7n+=+315+\"$
\n" ); document.write( " $\"+n+=+45+\"$
\n" ); document.write( "and
\n" ); document.write( " $\"+75+-+n+=+30+\"$
\n" ); document.write( "------------------
\n" ); document.write( "He answered 45 questions correctly
\n" ); document.write( "--------------------------------
\n" ); document.write( "check:
\n" ); document.write( " $\"+5n+-+2%2A%28+75+-+n+%29+=+165+\"$
\n" ); document.write( " $\"+5%2A45+-+2%2A30+=+165+\"$
\n" ); document.write( " $\"+225+-+60+=+165+\"$
\n" ); document.write( " $\"+165+=+165+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );