When a number is tripled, then decreased by 5 , the result is 16 . What is the original number?
(A) 3
(B) 5
(C) 7
(D) 9
(E) 11
Solution 1

To get back to the original number, we undo the given operations.

We add 5 to 16 to obtain 21 and then divide by 3 to obtain 7 .

These are the "inverse" operations of decreasing by 5 and multiplying by 3 .

## Solution 2

Suppose that the original number is $x$.

After tripling and decreasing by 5 , the result is $3 x-5$.

Therefore, $3 x-5=16$ or $3 x=21$ or $x=7$.

ANswer: (C)