Desarrollo :

1.    

V=180

R1=8    

R2=9

R3=27

R4=57

R5=60

1/Req: 1/8 + 1/9 + 1/27 + 1/57 + 1/60

1/REQ:769.5+684+328+108+102.6     /6156

1/REQ:1992.1/6156

REQ: 3.09

180/3.09=58.25

2.

2.

4.7k

6.6k

1.5k

9v

Req :4.7 x 6.6/4.7 + 6.6

Req:31.02/11.3

Req :2.745 *1.5/2.745+1.5

REQ :4.11 /4.24

REQ:0,969

 I =9/0.969

I=9.287

3.

6.8K

4.7K

1.5K

9V

REQ:6.8*1.5/6.8+1.5

REQ: 10.2/8.3

REQ:1.22

1.22+4.7=5.92

REQ:5.92

I:9/5.92

I=1.520

4.

6.0K

1.5K

4.7 K

9V

REQ:6.0*1.5/6.0+1.5

REQ:9/7.5

REQ:1.2

1.2 + 4.7=5.9

REQ=5.9

I=9/5.9

I=1.52 .