document.write( "Question 273290: On his last three math tests, mark scored 85,95, and 80. What grade must he get on his next test to have an average of 90 for all four tests? \n" ); document.write( "

Algebra.Com's Answer #199670 by JBarnum(2146) $\"\"$ $\"About$

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finding the average is where you add all the numbers up and divide by the number of numbers u have. so for this problem he will have 4 grades that will make him an average of 90.
\n" ); document.write( "so $\"%2885%2B95%2B80%2Bx%29%2F4=90\"$ add the numbers u can
\n" ); document.write( " $\"%28260%2Bx%29%2F4=90\"$ multiply by 4 to both sides of = sign
\n" ); document.write( " $\"%28%28260%2Bx%29%2Fcross%284%29%29cross%284%29=90%284%29\"$
\n" ); document.write( " $\"260%2Bx=360\"$ subtract 260
\n" ); document.write( " $\"x=100\"$
\n" ); document.write( "so the student has to get a $\"highlight%28100%29\"$ on the next test to get an average of $\"90\"$ \n" ); document.write( "

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