Sorry the picture is blurry. i don't understand subsitution and need . me i'm failing math and this will hopefully get my grade up

Okay so what you need to do is find the value of x or y. Substitute x or y for 0. After you do that, you'll be left with x on one side and y on the other. That's perfect. If x is alone, you want to substitute that into the equation, In parentheses. Then when you solve for the other term, you'll actually get a number answer. Then put that into the equation and substitute it where it should go, then solve and you'll get the second number

Assuming you want us to answer question 12.
11x - 7y = -14 
x - 2y = -4 

From the second equation, you can find x by adding 2y to both sides.
x = 2y - 4

Now that you've found what x is, go back to the first equation 11x - 7y = - 14
But now, wherever you see x in this, substitute in what you found for x. 
Our value for x is 2y - 4. 
11(2y - 4) - 7y = -14
Expand and simplify
22y - 44 - 7y = -14
15y - 44 = -14
15y = 30
y = 30/15 = 2

Now we know what y is, lets find x as a number.
Use what we found as x to find it as a number (x = 2y - 4), but substituting in 2 wherever we see 'y'.
So x = 2(2) - 4
= 4 - 4 = 0

So x = 0 and y = 2

Letter b hope it