Use the symbolic toolbox.
Move all of the initializations of constants first.
Then
syms cc cp ca co
and convert each of those things like f(cc)=EXPRESSION initial VALUE to
eqns(1) = EXPRESSION == VALUE
then
sol = solve(eqns, [cc, cp, ca, co])
then at the end,
fc = vo * sol.cc;
fp = vo * sol.cp;
fa = vo * sol.ca;
fo = vo * sol.co;
tau = V/vo;