Use the substitution method to solve x=2y+4 and y-2x=16

Which of the following are arithmetic sequences? check all that apply. a. 0.3, 0.6, 0.9, 1.2, 1.5, b. 2, 3, 6, 11, 18, c. 150, 147, 144, 142, d. 2, 4, 9, 16, 25,