a + b = 8 si b + c = 9
2 a + 5 b + 3 c = 43
= 2 a + ( 2 b + 3 b ) + 3 c =
= 2 × ( a + b ) + 3 × ( b + c ) =
= 2 × 8 + 3 × 9 =
= 16 + 27 =
= 43
2a+5b+3c=2a+2b+3b+3c=2(a+b)+3(b+c)=2*8+3*9=16+27 = 43
