In a class, there are three types of students: those who play football, those who play basketball, and those who play both. If 10 students play football, 8 play basketball, and 3 play both, how many students play only football?
Five tasks P, Q, R, S, and T need to be completed. Task P must be done before Q and R. Task S must be done before T and after R. What is the correct order of tasks?
In a mixed letter coding system, if the word 'CAT' is coded as 'XZY', and 'DOG' is coded as 'ABC', what is the code for 'AT' if 'A' is coded as 'X' and 'T' is coded as 'Y'?