18
votes
5answers
620 views

Cross Multiplying Two Fractions with Ovals Around the Appropriate Terms

I would like to implement something akin to the following in LaTeX, perhaps in tikz. I would be very grateful for any help.
9
votes
1answer
482 views

Automatically add fractions and reduce the result (if neccessary)

I'm trying to figure out how to reduce fractions. Adding fractions is no problem, see this example: \documentclass[parskip]{scrartcl} \usepackage[margin=15mm]{geometry} \usepackage{tikz} ...