1-а = 220/300 + 90/3001-а = 310/3001-а = 31/30
2/18 + c = 1 - 12/182/18 + c = 18/18 - 12/182/18 + c = 6/18c = 6/18 - 2/18c = 4/18c = 2/9
1-а = 220/300 + 90/300
1-а = 310/300
1-а = 31/30
2/18 + c = 1 - 12/18
2/18 + c = 18/18 - 12/18
2/18 + c = 6/18
c = 6/18 - 2/18
c = 4/18
c = 2/9