(4x+1), (4x+3), (12x+1) are the first three in an arithmetic sequence, solve for x.
4x + 3 - (4x + 1) = 2
So we must have 12x + 1 - (4x + 3) = 2
8x - 2 = 2
8x = 4
x = 1/2
+4 
