x=0,1(06)

10x=1,(06)

1000x=106,(06)

1000x-10x=990x=105

x=105/990=35/330

x=0,2(375)

10x=2,(375)

10000x=2375,(375)

10000x-10x=9990x=2373

x=2373/9990=791/3330

x=0,72(5)

100x=72,(5)

1000x=725,(5)

1000x-100x=900x=653

x=653/900