What is the percentage rate of increase per unit of x to the nearest tenth of a percent of y=1200(0.86)^4x

Eight people were asked what the balance of their savings account at the beginning of the month was and how much it increased or decreased by the end of the month. create a scatter plot that represents the data that is shown in the table. the x-axis represents the beginning balance in thousands of dollars and the y-axis represents the change in the savings account in hundreds of dollars. name beginning balance (in thousands of dollars) change in savings account (in hundreds of dollars) jimmy 5 3 kendra 4 7 carlos 5 4 yolanda 3 1 shawn 2 5 laura 3 2 andy 5 6 georgia 4 3

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Last month, a 770 g box of cereal was sold at a grocery store for $3.10. however, this month, the cereal manufacturer launched the same cereal in a 640 g box, which is being sold at $2.50. what is the percent change in the unit price?