Function to extract coeffcient for a given term
Basic solving rational expression exercise
Add answer and fraction simplification
Ensure variables don't cancel
Rename Simplifying rational expressions 4, Linear equations 4
Improve appearance of hints
Add exercise where rational expression equals a fraction
Merge branch 'solve-rat-exp' of https://github.com/petercollingridge/khan-exercises

Conflicts:
	exercises/linear_equations_4.html