Which equation shows the substitution method being used to solve the system of linear equations?
x – y = 7
x = y + 3
Ax = (7 – x) + 3
Bx – (y + 3) = 7
C(y + 3) – y = 7
Dx – y = y + 3
x – y = 7
x = y + 3
Ax = (7 – x) + 3
Bx – (y + 3) = 7
C(y + 3) – y = 7
Dx – y = y + 3