t'=(t-vx/cc)/g shows t' being greater than t.

The reason Special Relativity will not allow the
use of its basic time equation in determining what
SR has to say about the twins' ages, is that t' and
x' are supposedly just coordinates, and they say you 
have to take the coordinate pairs (t',x') and (x,t)
into consideration in both the time and place the 
twins' separation started and the time and place the 
twins reunited.

Since t' and x' are actually both intervals, not
just coordinates, the 'excuse' is spurious, and is 
so even without use of the obvious (x_b-x_a) and
(t_b-t_a) usages.

However, SR is right to be embarrassed by their
transformation formulas.

Look for the "(SR) Lorentz t', x' = degraded measures"
document at a newsgroup near you.