Andy has grades of  84,65,76 on three maths tests . What grade must he obtain on the next test to have anaverage of exactly 80 for the four tests ? How to solve it ?

 Marks: 84 65 76

But Avg needed in 4 tests is 80

Let the mark be in 4th test be x

Average=Totalmarks/no of tests

80=76+65+84+x/4

225+x=80*4

x=320-225

  =95 marks

Hope this helps Thumbs Upp plss

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