Core topics
Percent and ratio strength
Translate % w/v, % w/w, and ratio strengths into working concentrations before solving quantity problems.
Dilution
Use C1V1 = C2V2 when appropriate, confirming which concentration and volume pair belongs to stock versus final preparation.
Alligation concepts
Practise setting up allegation grids for mixing two strengths to a desired middle strength, then check parts against total quantity.