As in the above branch potential across $PQ$ is $6 \mathrm{V}$ and equivalent resistance is $3 \mathrm{\Omega }$ , therefore current in this branch should be $2 \mathrm{A}$ . Therefore voltage across $6 \mathrm{\Omega }$ is $4 \mathrm{V}$ and hence current in it is $\frac{2}{3} \mathrm{A}$ .