Question

Substitute x+2y=8 3x+2y=6

Answer 1

Use x+2y=8
Subtract 2y to make
x=8-2y

Plug this in to the other equation
3(8-2y)+2y=6

Distribute the 3
24-6y+2y=6

Combine like terms
24-4y=6

Solve
18/4=y, 9/2=y

Plug and solve for x
X+2y=8
X+(2*9/2)=8
X+9=8
X=-1

Answer 2

X + 2y = 8

3x+2y = 6

x + 2y =8
   -2y     -2y

x = 8 - 2y

Now replace the value for x into the second equation. 

3(8-2y) - 2y

Distribute property

3*8 = 24
3*2y = 6y

24 - 6y - 2y = 6

24 - 8y = 6
-24           -24 

-8y = -18

-8y/8 = -18/8

y = 2.25

Now replace the value for y into the equation.

x + 2(2.25) = 8
x + 4.5 = 8
    -4.5     -4.5

x = 3.5

Now we have our two values.

x = 3.5
y = 2.25