Given the following multiple regression equation: y = 49 + 10x1 - 4x2 - 3X3 Select the direction of change in y and enter a positive integer in the answer box. a) If 1 increases by 6 unitof while holding x2 and 3 constant, then y [Select an answer v ] by units on average. b) If 12 increases by 3 units while holding 1 and @3 constant, then y Select an answer v] by units on average. c) If x3 increases by 5 units while holding x1 and 2 constant, then y [Select an answer v] by units on average