no 20,21,22 aja sama penjelasan nya

20.I masuk=I kluar
1+4=5+1+x
5=6x
x=6-5=1
21.Rp=1/6+1/3+1/2=6/6=1
Rs=10+5=15
Rt=15+1=16ohm
22. 4x20=80x5=400
2x10=20x5=100
3x40=120x5=600
600+400+100=1100wh=11kwh
11x500=5500x30=Rp16500