The file extension is *.mcd indicating earlier Mathcad not Prime.
In Prime on the ribbon at the top go to input/output tab.
Third icon from the left is XMDC,MCD Converter. Select this icon and a dialog box opens. You can add *,mcd files, and then convert them. It places the new converted files in the same directory with same name and an *.mcdx extension so Prime can read them.
I have done this with the enclosed file. Works Ok with some setting out problems.
You need to go to Prime ribbon "Document" tab, to the "draft" view to see all the calculations to the right of the page width.
I checked the converted file. In the conversion process it sometimes treats units as variables. You have to manually change these "unit variables" to units.
Have done this for your file.
it worked fine
even I tried another way,
mathcad prime was giving me 1 error while converting these files as,
turn on/Click ok "net framework 3.5 windows feature is enabled"
I tried with that option and it worked fine.
thank you for your help and time.
I really appreciate it