This is the concept of simultaneous equations, given that the system of equations has two unknowns, the number of solutions to this equation should also be two.
Solving the equations we get:
x-3y=-8
x+3y=8
adding the above equations we get:
2x=0
thus
x=0
but from the bottom equation;
x+3y=8
substituting the value of x we get;
3y=8
thus;
y=8/3
the answers are:
x=0,y=8/3