Question

Stiind ca ca a+ b=10 si b- cb=12,calculeaza 3×a+7×b+4×c.

Va rog sa ma ajutati este URGENT!!!

Answer 1

 

a + b = 10

b + c = 12

3×a+7×b+4×c =

= 3a + 7b + 4c =

= 3a + 3b + 4b + 4c =

= 3(a+b) + 4(b+c) = 3 × 10 + 4 × 12 = 30 + 48 = 78

Answer 2

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 ( b + c ) =

= 3 x 10 + 4 x 12 =

= 30 + 48 =

= 78