The value of voltage V1 is 35 V.

Calculation:

The circuit diagram is redrawn as shown in Figure 1.

Write the expression for KCL at node A in Figure 1.

  −i1+V1R2+V1−vBR3=0   ..... (1)

Here, i1 is the current in the circuit, V1 is the voltage at node A, vB is the voltage at node B and R2, R3 are the resistances in the circuit.

Substitute 12 mA for i1, 5 kΩ for R2 and 5 kΩ for R3 in equation (1).

  −12 mA+V15 kΩ+V1−vB5 kΩ=0( 5 kΩ)( −12 mA)+V1+V1−vB5 kΩ=0( 5× 10 3  Ω)( −12× 10 −3  A)+2V1−vB5 kΩ=0−60 V+2V1−vB=0

Rearrange further.

  2V1−vB=60 V   ..... (2)

Write the expression for KCL at node B in Figure 1.

  vB−V1R3+vBR4+vBR5=0   ..... (3)

Here, R4 and R5 are the resistances in the circuit.

Substitute 5 kΩ for R3, 4 kΩ for R4 and 4 kΩ for R5 in equation (3).

  vB−V15 kΩ+vB4 kΩ+vB4 kΩ=04( v B − V 1 )+5vB+5vB20 kΩ=04vB−4V1+10vB=0−4V1+14vB=0

Rearrange for vB.

  vB=4V114

Simplify further.

  vB=0.286V1

Substitute 0.286V1 for vB in equation (2).

  2V1−0.286V1=60 V1.714V1=60 VV1=60 V1.714=35 V

Conclusion:

Thus, the value of voltage V1 is 35 V.