Question

Daca a+b=20 si b+c=10 calculati 5a+5b ; 9b+9c; 5a+14b+9c

Answer 1

a + b = 20   si  b + c = 10

5 a + 5 b = 5 ( a + b ) = 5 × 20 = 100

9 b + 9 c = 9 ( b + c ) = 9 × 10 = 90

5 a + 14 b + 9 c = 190

= 5 a + ( 5 b + 9 b ) + 9 c =

= 5 ( a + b ) + 9 ( b + c ) =

= 5 × 20 + 9 × 10 =

= 100 + 90 =

= 190