3
-4
(3 + (-4) + 1 = 0
-4 + 0 + 1 = -3
-3 + 0 + 1 = -2
-2 + (-2) + 1 = 1
3, -4, 0, -3, -2, 1
5-2a = 2
-2a = 2-5
-2a = -3
a = 1,5