Automation: get text from description field and paste it in summary field

[Patrick Vijgeboom]

We have two automations that contains two text strings I want to copy and paste it into the summary field. Below shown in BOLD is the text I want to copy and very's each ticket. The text in Italic is always the same. There is more text in the description but is not relevant. 

Datum in dienst: 01-12-1970
Naam medewerker: Obi Wan Kenobi

The text before both : is always the same. I want to past it to the summary field as follows:

In dienst nieuwe medewerker Obi Wan Kenobi per 01-12-1970