Answer :
[tex]x-\ registration\ fee\\
y-\ monthly\ fee\\\\
\left \{ {{x+4y=370} \atop {x+6y=530\ \ |*(-1)}} \right. \\\\
\left \{ {{x+4y=370} \atop {-x-6y=-530}} \right. \\+-----\\Addition\\\\
-2y=-160\ \ | divide\ by\ -2\\
y=80\\\\
x=370-4y=370-4*80=370-320=50\\\\
Registration\ fee\ is\ equal\ to\ 50\$\ and\ monthly\ fee\ is\ equal\ to\ 80\$.
[/tex]