The impedance of the load is 18.2 ohm \/ -43.3.
The current through the source is 12.2 A \/ 41.4
Hint for 7.16
The unbalanced load impedance is 145 ohm \/ 36.9 deg.
Harder way: You may add a capacitor in parallel to this impedance and determine when the effective net reactance is zeroed.
Easier way: Evaluate the reactive power when unbalanced and use that quantity to determine what capacitive reactance is required.
Hint for 7.17
Calculate the real and reactive power for each appliance and add to find the apparent power.
Hint for 7.20
w/o C: Q = -750 VAR
with C: Q = -330 VAR desired
What additional reactance is needed to provide the difference?