Question

x+y=8 si y+2z=35,calculati:7x+10+6z

Answer 1

1) x+y=8
    y+2z=35
2) y=8-x
    2z=35-8+x

7x+10+3(35-8+x)=0
7x+10+105-24+3x=0
10x=91
   x=9.1

Answer 2

7x+10y+6z=?

x+y=8, inmultim cu 7 si obtinem rel.(1) 7x+7y=56
y+2z=35, inmultim cu 3 si obtinem rel.(2) 3y+6z=105

Adunam rel (1) si (2) si obtinem 7x+10y+6z=56+105=161