[tex]\begin{gathered} \text{first, the conversationist catched 141 trout}s\text{ and tagged them,} \\ \text{the he catches 45 trouts, but he tagged only 15 of them. That means } \\ 30\text{ of the 45 trouts were already tagged } \\ \text{ so he only found 15 new trouts, and in total he would expect there are } \\ 141+15=156\text{ trouts} \end{gathered}[/tex]