Calculate a column using other two using date condition

Hi folks , I have one table with these columns .

Closed | Closed things Cumulative Closed things

20/4/2018 | 2 | 2

22/4/2018 | 2 | 4

25/4/2018 | 5 | 9

'Actual opened things'

*THIS IS THE COLUMN I WANT TO CALCULATE

Which I want to be a Cumulative column which subtracts with the 'cumulative Closed things' only if

it has values on that date.*

Opened | Opened things | Cumulative Open things | Actual opened things

15/4/2018 | 10 | 0+10=10 | 10-0=0

17/4/2018 | 6 | 10+6=16 | 16-0=16

21/4/2018 | 9 | 16+9=25 | 25-2=23

26/4/2018 | 11 | 25+11=36 | 36-9=27

I want to see in each date how many things are opened , with that being said I want for each date Cumulative Open Things - Cumulative Closed Things (only if it has closed things on before that date )

Appreciate any help on Dax or something like that .

Thanks guys. Anything you don't understand please let me know .