Determine the power delivered
by the 30 A source.
First, express the 30 A source in terms of mesh currents.
I3 = 30
Now removing the 30 A source leaves only two meshes, 1 and 2.
KVL around mesh 1.
4 I1 + 16 I1 - 16 I2 + 5.6 I1 - 5.6 I3 - 600 = 0
25.6 I1 - 16 I2 - 5.6 (30) = 600
25.6 I1 - 16 I2 = 768 (Eq. 1)
KVL around mesh 2.
3.2 I2 + 424 + 0.8 I2 - 0.8 I3 + 16 I2 - 16 I1 = 0
- 16 I1 + 20 I2 - 0.8 (30) = - 424
- 16 I1 + 20 I2 = - 400 (Eq. 2)
Solving the two equations yields:
I1 = 35 A
I2 = 8 A
Now, to find the power delivered by the 30 A source, find the voltage across it using KVL.

First find V1 and V1 with Ohm's Law.
V1 = 5.6 (I3 - I1) = 5.6 (- 5) = - 28 V
V2 = 0.8 (I3 - I2) = 0.8 (22) = 17.6 V
KVL yields:
VS = V1 + V2 = - 10.4 V
So the power delivered to the circuit by the 30 A source is
P = 30 (- 10.4) = - 312 W
so the 30 A source is actually absorbing power.