1) х + 9/20 = 3/4
х = 15/20 - 9/20
х = 6/20 = 3/10
6/20 + 9/20 = 3/4
15/20 = 15/20
ответ: х = 6/20; 3/10
2) 25/36 - х = 5/18
25/36 - х = 10/36
х = 25/36 - 10/36
х = 15/36 = 5/12
25/36 - 15/36 = 5/18
10/36 = 10/36
ответ: х = 15/36; 5/12
1) х + 9/20 = 3/4
х = 15/20 - 9/20
х = 6/20 = 3/10
6/20 + 9/20 = 3/4
15/20 = 15/20
ответ: х = 6/20; 3/10
2) 25/36 - х = 5/18
25/36 - х = 10/36
х = 25/36 - 10/36
х = 15/36 = 5/12
25/36 - 15/36 = 5/18
10/36 = 10/36
ответ: х = 15/36; 5/12