Answer :

[tex]12.9:0.6=129:6=(120+9):6=120:6+9:6\\\\=20+(6+3):6=20+6:6+3:6=20+1+3:6=21+3:6\\\\Answer:\\\\12.9:0.6=21+3rest\\\\or\\\\12.9:0.6=21+3:6=21+\frac{3}{6}=21+\frac{1}{2}=21\frac{1}{2}=21.5[/tex]