How many marbles does Sanjay have ? I. Sanjay has 3 times more marbles than Ahmed. II. Ahmed has one third the number of marbles which Suresh has who has as many marbles as Sanjay.

Data sufficiency questions are designed to check your ability to analyse & categorise information based on underlying concepts rather than calculations. So you should try to observe -  analyse and to find linkages between various statements rather soing lengthy calculations.