Solving a system of nonlinear equations

Hello!

How can I make MAPLE to put out the numerical solution of the following system?
(a =0.12, c = 47.04)  Neither solve nor fsolve does the job!

Thank for your help!

>restart:
>S:=t->c*exp(-a*t)+18;

                      S := t -> c*exp(-a*t)+18

> sys:={S(2)=55,S(8)=36};

        sys := {c*exp(-8*a)+18 = 36, c*exp(-2*a)+18 = 55}

> solve(sys);

         {a = -1/2*ln(18/37*RootOf(18*_Z^3-37)^2), c = 37*RootOf(18*_Z^3-37)}

> fsolve(sys);

         fsolve({c*exp(-8*a)+18 = 36, c*exp(-2*a)+18 = 55},{a, c})