a-b=53
b-c=31
c=a/4 = > a = 4c
-------
a+b+c=?
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I.
Inlocuim a = 4c in prima relatie
4c-b = 53
b-c = 31 (se inmulteste toata ecuatia cu 4 )
4c-b = 53
4b-4c = 124 ( inversam a II-a a.i sa avem c inaintea lui b fara a schimba ecuatia)
4c-b = 53
-4c+4b = 124
---------("+")
-b+4b = 177
3b = 177
b = 59
Revenim in prima relatie:
a-59=53
a = 112
Daca c = a/4 => 112/4 = 28
=> c = 28
a = 112
b = 59
II.Verificare.
a-b = 53
112-59 = 53 Adevarat
b-c = 31
59-28 = 31 Adevarat
c = a/4
28 = 112/4
28 = 28 Adevarat
a+b+c = 59+112+28 = 59+140 = 199