Explanation:
When it says x = something, that basically means to replace the x with whatever it says x equals.
x = 0. Equation /. 3 x 0 = 0 + 1 = 1. Y = 1
x = -1. Equation/. 3 x -1 = -3 + 1 = -2. Y = -2
x = 2. Equation/. 3 x 2 = 6 + 1 = 7. Y = 7
Hope this helps!! (: