Question

Stiind ca a+b=10 si b+c=12 calculeaza:
3xA+7xB+4xC

Answer 1

a + b = 10   si  b + c = 12

3 x a + 7 x b + 4 x c = 78

= 3 x a + ( 3 x b + 4 x b ) + 4 x c =

= 3 x ( a + b ) + 4 x ( b + c ) =

= 3 x 10 + 4 x 12 =

= 30 + 48 =

= 78