#### Answer

$x=3$

#### Work Step by Step

Let the unknown number be $x$.
The sum of 4 and three times this number is represented by the expression $(4+3x)$.
The sum of this number and 10 is represented by the expression $(x+10)$.
Since the sum of 4 and three times a certain number is
the same as the sum of the number and 10, we obtain:
$4+3x=x+10$
$3x-x=10-4$
$2x=6$
$x=\frac{6}{2}=3$