**Solution** :

Let the number be $a$ and $b$.

$\therefore$ According to question,

$a+b=29$...(1)

and $a^{2}-b^{2}=145 \quad$...(2)

We know that,

$$

\begin{aligned}

& a^{2}-b^{2}=(a+b)(a-b) \\

\Rightarrow & 145=29(a-b) \\

\therefore \quad & a-b=\frac{145}{29}=5 ; \text { Ans. }

\end{aligned}

$$