6) Problem on Numbers

A number is doubled and 9 is added. if the resultant is trebled, it becomes 75. What is the number?
(A) 3.5  (B) 6  (C) 8  (D) None of these
Answer: C
Description:
Let the number be x. Then 3(2x+9)=75 , 
<==> 2x+9=25<==>2x=16
X=8..