HELP!!

Solve the system using addition.
7 x plus 2 y
equals
negative 13
negative 7 x plus y
equals
25

Select the quadratic that has root x = 8 and x = -5

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.

Could someone with number 1 and 2