# MATLAB: Solve with known variables

MATLABsolvevariables

Probobly basic but I've been trying for hours with Googleing and trying different things. Any help would be appricated.
All I'm trying to do is substitute the known variables (a,b,c) into eqn2 in this case and I cannot get S to spit out 1000 as I think it should.
Code:
a = -500;
b = 433;
c = -866;
syms a b c
eqn2 = (-0.5*a-0.866*c) == 1000;
S = solve(eqn2,[a,c])

syms a b c% a = -500;b = 433;% c = -866;eqn2 = (-0.5*a-0.866*c) == 1000;S = solve(eqn2,[a,c]);a = S.ac = S.c
a =-2000 c =0