"Do I demonstrate it to you?"
Translation:Je te le démontre ?
On principle, if you have 2 pronouns, one indirect object and one direct object, you place the direct object pronoun stuck right in front of the verb:
- il (subject) y (indirect) en (direct) a (verb) beaucoup. (There are many of them)
- je (subject) lui (indirect) en (direct) ai parlé (verb). (I told him about it)
(There may be exceptions, but I can't think of any at this moment). I found a pdf for you: http://www.laits.utexas.edu/tex/pdf/pro9.pdf