Algebra with Fractions basics - help for KS5 (or KS4)

This question sheet is aimed at A Level students who are struggling to do simple algebraic manipulation where fractions are involved. For the most part these are not typical 'algebraic fractions' questions (e.g. adding algebraic fractions), but are more basic than that. For example, I have encountered students who are otherwise working at fairly high grades but are unable to differentiate, say, 3x/4 because they cannot see that it is equivalent to 3/4× x (and hence simply x multiplied by a constant). Another issue is that students quite often ‘simplify’ fractions by trying to cancel in invalid ways.