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daca a+b=29 si b+3xc=21,atunci 3xa +5xb+6xc=?


a)127 b)128 c)129


REPEDEE ! DAU COROANA


Răspuns :

a + b = 29 => 3a + 3b = 29×3= 87
b + 3c =21 => 2b + 6c = 21 × 2 = 42
(3a + 3b) + (2b+ 6c) = 87+42
3a + 5b + 6c = 129