SOLUTION: A student has taken four tests in a class... earning scores of 84,80,95,91. What must the student score on his/her last test to earn an average of 90?

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Question 639499: A student has taken four tests in a class... earning scores of 84,80,95,91. What must the student score on his/her last test to earn an average of 90?
Answer by Tatiana_Stebko(1539) About Me  (Show Source):
You can put this solution on YOUR website!
%2884%2B80%2B95%2B91%2Bx%29%2F5=90
%28350%2Bx%29%2F5=90 Multiply by 5
350%2Bx=450
x=100