a + b + c = 54
2b = a + c
c = a + b - 28
a + b + c = 54
- a - b + c = - 28
le adunam
2c = 26
c = 26 : 2
c = 13
a + b + c = 54
a + b - c = 28
le adunam
2a + 2b = 82 | : 2
a + b = 41
a = 41 - b
2b = 41 - b + 13
2b + b = 41 + 13
3b = 54
b = 54 : 3
b = 18
a = 41 - 18
a = 23