Enrique has two options to pay for texts on his cell phone. he can add an unlimited text package for $20 each month, or he can pay $0.20 for each text sent or received. (the cost for each plan is graphed below.) what is the solution for the system that models this scenario? a. (20, 20) b. (50, 20) c. (100, 20) d. (250, 20)

17. a researcher measures three variables, x, y, and z for each individual in a sample of n = 20. the pearson correlations for this sample are rxy = 0.6, rxz = 0.4, and ryz = 0.7. a. find the partial correlation between x and y, holding z constant. b. find the partial correlation between x and z, holding y constant. (hint: simply switch the labels for the variables y and z to correspond with the labels in the equation.) gravetter, frederick j. statistics for the behavioral sciences (p. 526). cengage learning. kindle edition.