X-2/3=3/2. 2/5+x=1 2/15. (x-2/5)-0,3=2 1/4

1)
х-2/3=3/2
х=3/2+2/3
х=2цел1/6

2цел1/6-2/3=3/2
3/2=3/2
ответ:2 цел1/6

2)
2/5+х=12/15
х=12/15-2/5
х=2/5

2/5+2/5=12/15
12/15=12/15
ответ:2/5

3)
(х-2/5)-0,3=21/4 0,3=3/10
х-2/5=21/4+0,3
х-2/5=4цел19/20
х=4цел19/20+2/5
х=5цел7/20

(5цел7/20-2/5)-0,3=21/4
21/4=21/4
ответ: 5цел7/20