Let i1 and i2 be current drawn from battery 15 V and 30V, respectively as shown below
Hence, by KCL. Net current passing through branch BD i3=i1+i2 ...(i) By KVL, in loop ABDA, 15−6i1−3(it+i2)=0 ⇒−6i1−3i1−3i2=−15 ⇒3i1+i2=5 ...(ii) In loop CBDC,30−3i2−3(i1+i2)=0 ⇒i1+2i2=10 ...(iii) By solving Eqs. (ii) and (iii), we gel i1=0 and i2=5A Substituting these values in Eq. (i), we get Current through branch BD, i3=i1+i2=0+5=5A