(a) The second term is a d= x - 1 while the fourth term is a + 3d = x + 1. Subtracting the second tam from the fourth term yielded 2d = 2 so that d = 1.~(b). Substituting for d in the expression for the sixth term to get a + 5 = 7 and solving for a to obtain a = 2.
(c). Substituted for a and d in the expression for the second term and found x = 2 + 1 + 1 = 4.
~(c). Substituted for a and d in the expression for the second term and found x = 2 + 1 + 1 = 4.
