Question 823057
<pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
Solve by substitution.
x = {{{12-y}}}
6x-3y=9    |Substituting for x
6(12-y) - 3y = 9 
    -9y = -63
      y = 7
and   x = 5    {{{12-y}}}     
CHECKING our answer***
using: 6x-3y=9 
    30 - 21 = 9