Hi guys. I have a problem of calculate p1 in this question. p4=4x20=80W
p3=4x12=48W. p2=8x6=48W but how do you calculate p1? Theres only dependent current of 2 A known. Thanks

 

The diagram can tell you the value of I, as well as the voltage applied on the source P1. It just does that indirectly. Can you see it?

Hint: these quantities are defined by other sources.

 

is it 8V cos the current source is in parallel with the 8V

 

Yes. How about the current I. Can you find it?

 

yh 2 A. Thanks

 

Exactly. I is the same as the current flowing through source 4, as they are in the same branch. Thus the current through source 1 is 0.5I=2A.