#### Answer

$3$

#### Work Step by Step

We let the unknown number be $x$.
Two times the unknown number is $2x$ while one more than two times the unknown number is $(2x+1)$.
Four times the unknown number is $4x$.
The question states that one more than two times a certain number is five less than four times the number. This means that $2x+1$ is equal to $4x-5$.
Therefore, we write the following equation and solve:
$2x+1=4x-5$
$4x-(2x+1)=5$
$4x-2x-1=5$
$2x-1=5$
$2x=5+1$
$2x=6$
$x=3$
Therefore, the unknown number is $3$.