Q:    Find out the value of the voltage V_bd in given circuit

Solution:

            We need to calculate the voltage V_bd. As we may see there is no closed path between b & d, therefore the circuit may be redrawn like

We can let two closed paths abda & bcdb . The KVL equation for these two paths is written like this

            Applying the KVL equation for the loop abda

                                                            2 - V_bd -9 = 0

                                                          V_bd = -7 V

                                     Now KVL equation for the path  bcdb

                                                            4 + 3 + V_bd = 0

                                                                          V_bd = -7 V