Emil, if it is so simple you can do it. It is a guess, but I'd say there are 40 to 50 equations in that paper, not including the explanation of terms. Some of it is in the electrodynamics section and.., at least when I was in school was a little above high school math. I have trouble getting Tex formatted properly for simple algebra. Note: "That paper" was the introduction of SR, not the little book that followed in about 1920 and included an expanded explanation of both SR and GR.