In a sports club with 30 members, 18 play badminton and 19 play tennis and 2 do not play either. How many members play both badminton and tennis? Pick
A) 7  B) 8  C) 9  D) 10  E) 11

Rationale: "let x play both badminton and tennis so 18 - x play only badminton and 19 - x play only tennis . 2 play none and there are total 30 students . hence , ( 18 - x ) + ( 19 - x ) + x + 2 = 30 39 - 2 x + x = 30 39 - x = 30 x = 9 so 9 members play both badminton and tennis . c"
Answer: C