klepka2001 4,2=21/5
3/7õ=21/5
õ=21/5:3/7
õ=21/5*7/3
õ=49/5=9,8

evvoronina1 Õ-4/7õ = 4,2
õ-4 = 4,2•7õ
õ-4 = 29,4õ
29,4õ-õ = -4
28,4õ = -4
õ = -4/28,4
õ = -4/(284/10) = -10/71