van=facebook.com/LearningCalculus$

kill(all)$

f(t,s,m):= (1/(s*sqrt(2*%pi)))*%e^((-1/2)*((t-m)/s)^2);

A: f(t1,s,m)=o1;
B: f(t2,s,m)=o2;

A: log(f(t1,s,m)=o1), logexpand=super;

B: log(f(t2,s,m)=o2), logexpand=super;

fullratsimp(A-B);

rel: factor(fullratsimp(expand(A-B)));

solve(rel,m);

second(solve(rel,s));