output of below expression

What is postfix equivalent of
3 * log(x+1) - a/2 ???

Actually i just made a tree and then did a post traversal of the tree,so I got the answer to be 3log(x+1)*a2/- ,so I just wanted to know whether I am correct or not,becoz I am not able to understand how to tackle the log(x+1) part,so plz guide...