document.write( "Question 316966: the average mark of 4 tests is 72 if the numbers are 60 and 80 find the third number \n" ); document.write( "

Algebra.Com's Answer #226890 by JBarnum(2146) $\"\"$ $\"About$

You can put this solution on YOUR website!
dont u mean 3 tests since theres clearly no indication to find the 4th one and with a 2nd variable it would make for an incredible guess and check question with lots of possibilities. so im going to assume u meant 3 tests
\n" ); document.write( " $\"%2860%2B80%2Bx%29%2F3=72\"$
\n" ); document.write( " $\"%28140%2Bx%29%2F3=72\"$
\n" ); document.write( " $\"%28140%2Bx%29=216\"$
\n" ); document.write( " $\"x=76\"$
\n" ); document.write( "

\n" ); document.write( "just to show u what the problem would be with 2 unknowns:
\n" ); document.write( " $\"%2860%2B80%2Bx%2By%29%2F4=72\"$
\n" ); document.write( " $\"%28140%2Bx%2By%29=288\"$
\n" ); document.write( " $\"%28x%2By%29=148\"$
\n" ); document.write( "as u can se there are many possibilities for what x or y could be, which would make a question like this unanswerable.
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\n" ); document.write( "good luck \n" ); document.write( "

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