To find the voltage v over the resistance and capacitance I use the fact that the entire current will go through the equivalent resistance and the voltage (v) is then V=I_s/(80-j 40) and since I_s = 0.1 => V = 0.001 + j 0.0005 or in phasor notation: V = 0.001118033 ∠26.57°

The answer in the book is V = 8.944 ∠-26.56° but I don't see what I'm doing wrong...