document.write( "Question 870020: in an examination consisting of 15 questions,8 marks are awarded for a correct answer and 4 marks are deducted for a wrong answer,how many correct answer are needed to score 72 marks in this examination? \n" ); document.write( "

Algebra.Com's Answer #524635 by mananth(16946) $\"\"$ $\"About$

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correct answer-----------x
\n" ); document.write( "wrong answer-------------y\r
\n" ); document.write( "\n" ); document.write( "x+y=15\r
\n" ); document.write( "\n" ); document.write( "8x-4y=72\r
\n" ); document.write( "\n" ); document.write( "1.00 x + 1.00 y = 15.00 .............1
\n" ); document.write( "Total value
\n" ); document.write( "8.00 x -4.00 y = 72.00 .............2
\n" ); document.write( "Eliminate y
\n" ); document.write( "multiply (1)by 4.00
\n" ); document.write( "Multiply (2) by 1.00
\n" ); document.write( "4.00 x 4.00 y = 60.00
\n" ); document.write( "8.00 x -4.00 y = 72.00
\n" ); document.write( "Add the two equations
\n" ); document.write( "12.00 x = 132.00
\n" ); document.write( "/ 12.00
\n" ); document.write( "x = 11.00
\n" ); document.write( "plug value of x in (1)
\n" ); document.write( "1.00 x + 1.00 y = 15.00
\n" ); document.write( "11.00 + y = 15.00
\n" ); document.write( " y = 15.00 -11.00
\n" ); document.write( " y = 4.00
\n" ); document.write( " y = 4.00
\n" ); document.write( "11 correct answers \n" ); document.write( "

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