a+d = 60
d+c = 68
a+ c = 76
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2a+2d+2c = 60+68+76
2(a+d+c) = 204
a+d+c = 204:2
a+d+c = 102
60+c = 102
c = 102-60
c = 42 stelute a decupat corina
a+68 = 102
a = 102-68
a = 34 stelute a decupat ana
d+76 = 102
d = 102-76
d = 26 timbre a decupat diana
Proba
34 + 42+26 = 76+26 =102