You take the first equation and make a value for y. So 6x + y =7 change it to :
y = -6x + 7
Now in the second equation replace the “y” with -6x +7 this is what it means to use substitution method . Your combined equation will now be :
8x + 9(-6x + 7) =17
Now do distributive property and you get :
8x + -54x +63 =17
Now combine like terms ;
-46x +63 =17
-46x =-46
x = 1
Now replace 1 for X value and we can get the value of Y .
Y=1
X=1