#### Answer

The number is $18$.

#### Work Step by Step

Let
$x$ = the unknown number
Then
"three times a number" means $3x$
"sum of five and three times a number" means $5+3x$
Thus, the equation that represents the situation is:
$5+3x=59$
Subtract $5$ on both sides of the equation to obtain:
$3x=54$
Divide $3$ on both sides of the equation to obtain:
$x=\dfrac{54}{3}
\\x=18$