## Elementary Algebra

$5$
Let the unknown number here be $x$. Four times a certain number is $4x$. 3 added to four times a certain number means $4x+3$. Therefore, if 3 is added to four times a certain number, the result is 23 means that: $4x+3=23$ Solving the above equation, we obtain: $4x+3=23$ $4x=23-3$ $4x=20$ $x=\frac{20}{4}$ $x=5$ Therefore, the unknown number is $5$.