Resposta:

Explicação passo a passo:

f.

12/6=30/x

12x=6.30

12x=180

x=180/12

x=15

12/6=36/y

12y=6.36

12y=216

y=216/12

y=18

g.

x+3/5x-2=4/7

7(x+3)=4.(5x-2)

7x+21=20x-8

7x-20x=-8-21

-13x=-29 (-1)

13x=29

x=29/13

h.

3/2=4x+1/3x

2(4x+1)=3.3x

8x+2=9x

8x-9x=0-2

-x=-2 (-1)

x=2