an equation that can be used to predict fuel economy in miles per gallon for automobiles is y = 41.3 - 0.004 x 1 - 0.0049 x 2 where x1 is the engine displacement in cubic inches x2 is vehicle weight in pounds. x1 = 305, x2 = 3750. use the given regression equation to predict the y-value for the given values of the independent variables.