I just read in e-book all about those three powers and seems like I understood the subject well but than this next problem gives me trouble:

first they ask to find average, reactive and apparent powers for 20Ω and i'm not sure how to do that. Assuming average they mean true power, Would i have to start with \(P_{real}=\frac {(60v<30)^2} {20ohms<0} \) ?

 

A pure resistance draws no reactive power. The real (average) and apparent power magnitudes for the 20Ω will therefore be the same.

In the case of a purely reactive element (say the 10Ω [reactance] inductor) no real power is drawn - only reactive power. For a purely reactive element the apparent and reactive power magnitudes will also be the same.