First, fint the roots of the equation 
1.
2. You can see that this equation has two different real roots. Note that you can make this statement without finding roots, only knowing the value of discriminant: since D=81>0, then the equation has two different real roots.
What's the question you're asking
If you plug in the x values of both (2, 8) and (4, 12) into each equation, you'll find that y = 2x + 4 gives you the correct y values for both (2, 8) and (4, 12). So that is your answer.
I am pretty sure that the answer is 3
I’m not really sure but I would have to guess 4.5 because all of the other numbers don’t have decimals
