Undefined variable "resolve" or class "resolve".

syms F G x y c
f='-x';
g='y';
c='solve';
F=char(f);G=char(g);
sol=abs(solve(G-F-c,y))
c=solve{subs(sol,x0*x)-y0,c}

[Walter Roberson]

Which release are you using?

Error using  - 
Matrix dimensions must agree.

That occurs when trying to subtract the character vector '-x' from the character vector 'y'

c=solve{subs(sol,x0*x)-y0,c}

Notice there you are trying to access solve as if it were a cell array.