To do this in vanilla Bubble you can do the following:
Take the list of numbers and use the :format as text operator
For each list item, enter (This Number/10) +5 and use , as the delimiter… that will output a single string: "10,15,8"
Use :split by , to split that into a list of texts ("10", "15", and "8")
Then use :each item converted to number to convert that list of texts into a list of numbers (10, 15, and 8)