I'll look over your equations once you use units properly (or at least make an honest attempt to).Ok! I got this equations and answers:
For V0:
8i0 = 6; therefore i0 = 6/8 = 0.75A in the resistance of 8 Ohm's
For i0:
6 = i0 + i0/4 = 6/1.25 = 4.8A
I am assuming that the book is rounding the current on the 8Ohm's resistor to 1. And not rounding the current of i0 to 5.