1) a × b + a × c + a = 749
a × ( b + c + 1 ) = 749
a × ( 106 + 1 ) = 749
a × 107 = 749
a = 749 : 107
a = 7
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2) 3 a + 2 b + 2 c = 45 si a + 2 b + 2 c = 99
( 3 a + 2 b + 2 c ) + ( a + 2 b + 2 c ) = 45 + 99
( 3 a + a ) + ( 2 b + 2 b ) + ( 2 c + 2 c ) = 144
4 a + 4 b + 4 c = 144
4 × ( a + b + c ) = 144
a + b + c = 144 : 4
a + b + c = 36