Ans : Linear functions are those whose graph is a straight line. A linear function has one independent variable and one dependent variable. The independent variable is x ( which is the distance Jacqueline travels ) dependent variable is y ( which is Speed, in mi/h )
Now the equation becomes : Speed (y) = Distance (D) / Time(X). Then the speed at which Jacqueline traveled :
y = D/X
y = 40/50 = 0.8 mi/minute
= 0.8 x 60 = 48 mi/hour.
We create a liner function and the two variables are x (Independent, Time) & y (Dependent, Speed). (D) is the coefficient of the independent variable x.