a + b + c = 288
daca ...
a - x = 12
b - x = 17
c - x = 19 Adunate termen cu termen , obtinem:
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a+b+c - 3x = 48
288 - 3x = 48
3x = 288 - 48
3x = 240
x = 80 => a = 12 + 80 = 92 ;
b = 17 + 80 = 97 ;
c = 19 + 80 = 99 ;
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Proba: a+b+c = ........ = 92+97+99 = 288 (adevarat )