Let \(\overline{ab}\) be the smaller number,then \(3\overline{ab}+3;\overline{ba}\) are the bigger number and the sum of 2 numbers \(\left(a,b\in Z^+;a,b\le9\right)\).We have :

\(3\overline{ab}+3+\overline{ab}=\overline{ba}\Rightarrow4\left(10a+b\right)+3=10b+a\)

\(\Leftrightarrow39a+3=6b\Leftrightarrow13a+1=2b\)

\(b\le9\Rightarrow2b\le18\Rightarrow13a+1\le18\Rightarrow a=1\Rightarrow b=\dfrac{13.1+1}{2}=7\)

\(\Rightarrow\overline{ab}=17\Rightarrow3\overline{ab}+3=17.3+3=54\)

So,2 numbers are 17 and 54