a+b+c = 1125
a = 2b
2c = a+b
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2c = a+b => 2c+c = 1125 => 3c = 1125 => c = 1125/3 = 375
a+b+375 = 1125 => a+b = 1125-375 = 750
a = 2b => 2b+b = 750 => 3b = 750 => b = 750/3 = 250
a = 2x250 = 500.
Proba:
a+b+c = 500+250+375 = 1125 (A)
a = 2b = 2x250 = 500. (A)
2c = a+b => 2x375 = 500+250 => 750 = 750 (A)