A number is doubled and 9 is added. If the resultant is trebled, it becomes 75. What is that number?  Pick:
A) 3
B) 4
C) 6
D) 8
E) 9
Sol.   Let the number be x.   Then, 3(2x +9) = 75   ⇔ 2x + 9 = 25   ⇔ 2x = 16   ⇔ x = 8   Answer 8
<result>D</result>
A number is doubled and 9 is added. If the resultant is trebled, it becomes 75. What is that number?