a + b + c = 18
2 a + b + 2 c = 25
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( 2 a + b + 2 c ) - ( a + b + c ) = 25 - 18 → scad relatiile date
2 a + b + 2 c - a - b - c = 7
a + c = 7
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( 2 a + b + 2 c ) + ( a + b + c ) = 25 + 18 → adun relatiile date
3 a + 2 b + 3 c = 43
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( a + c ) × ( 3 a + 2 b + 3 c ) = 7 × 43 = 301