Answer:
a) when (-1,-4) is substituted into the first equation
then the equation is satisfied
b) The ordered pair(-1, –4) is a solution to the system of linear equations.
Step-by-step explanation:
Step(i):-
Given that the system of equations
 x -y =3 ...(i)
 7x -y =-3 ...(ii)
subtracting (i) and (ii) equations , we get
  x -y  -(7x-y) = 3 -(-3)
  x - y - 7x + y = 6
     - 6x = 6
       x = -1
Step(ii):-
Substitute x=-1 in equation (i), we get
    x -y =3
   -1 -y = 3
    y = -1-3
    y = -4
The solution of the given system of equations (-1,-4)
Final answer:-
a) when (-1,-4) is substituted into the first equation
then the equation is satisfied
b) The ordered pair(-1, –4) is a solution to the system of linear equations.