Write and solve an inequality for the problem.

 

   Ann's Grade is the average of four scores:three chapter tests and a final that counts as two chapter tests.     

   She scored 72, 90, and 75 on the chapter tests.     

   what score does she need on the final to have a grade of at least 80?     

 

   (72 + 90 + 75 + 2x ) / 5  =  80     

   (72 + 90 + 75 + 2x )       =  5 • 80 = 400     

                  237 + 2x          =  400     

                            2x          =  163     

                                      x  =  81.5  or higher     

   _.