Question

Which equation shows the substitution method being used to solve the system of linear equations?

Answer 1

The equation
(y + 5) + y = 6
shows the substitution method being used to solve the system of linear equations. So the correct option among all the options given in the question is option "D".
For a better explanation, let us first write down the two equations given in the question.
x + 5 = 6
and
x = y + 5
Now the thing that has been done is that the value of x in the first equation has been replaced by the value of x that is given in the second equation. this is actually the substitution method of solving equations.

Answer 2

Your answer is D. You're welcome ;-) (Not trying to sound sarcastic, just I wanted to say you're welcome now than never)