Try this:
syms a b c
Eqn = (3*a)/8 + (3*b)/8 + c/4
[Eqnn,Eqnd] = numden(Eqn)
producing:
Eqnn =
3*a + 3*b + 2*c
Eqnd =
8
Unfortunately, if you express it again as:
NewEqn = Eqnn / Eqnd
the result is the original format for ‘Eqn’.
EDIT —
The best you can hope for is a LaTeX expression for your fraction:
syms a b c
Eqn = (3*a)/8 + (3*b)/8 + c/4
[Eqnn,Eqnd] = numden(Eqn)
fn = latex(Eqnn);
fd = latex(Eqnd);
Expr = sprintf('$f(a,b,c) = \\frac{%s}{%s}$', fn, fd)
producing:
