x=-198(substitute the value of x into the equation)
x-6y=90
-198-6y=90(solve the equation)
y=-48(a possible solution is)
(x,y)=(198,-48). (check yhe solution)
-198-12= 210(simplify)
-198-6(-48)=90
-210=-210( the ordered pair is a solution)
90=90
(x,y)=(198,-48)
is the answer