Out of 64 students 38 play both chess and cricket. How many students play only chess? I. Out of 64 students 22 students don't play any game. 4 students play only cricket. II. Out of 64 students 20 are girls and 10 of them don't play any game.

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.