Finding Thevenin voltage without a known current

[noname1]

On the first image i have to find the thevenin equivalent viewed from terminals x, x' & y, y'

i get the Req as 7.32ohms but now i am having trouble calculating the vth, i have no I to calculate

thanks in advance

 

[willem2]

Are you sure you put in the right picture? I see no terminals a&b, but only x,x',y and y'.

V_th is R_th * (current if you short the output terminals)

 

[noname1]

Yes i am sorry its terminal x, x' & y, y'