I have Windows 10 installed on my computer and I'm going to install Ubuntu 19.10 in dual boot. However, I don't know how to manage my disk partitions (either from Windows 10 or the Ubuntu bootable key) to achieve this without losing Windows (it happened to me several times before).
This is what the Windows Disk Manager looks like:
Edit: This is what I got when I tried to boot from a live USB. Does this mean my old Ubuntu installation is still there?
What's in partitions 7 and 8? They're not NTFS, nor FAT32, so please confirm they have no data to save. Once you have confirmed that, you can delete them in Windows Disk Manager, then proceed with installing Ubuntu in that empty space.
If you used that space for Ubuntu before, wne you boot with a liveUSB, it will appear as ext4 (the standard Ubuntu partition type). Check it with your LiveUSB you were going to use to install to see what it is.
The 192 GB (combined) of space freed up by 7 & 8 is more than enough for Ubuntu; 50GB is more than enough for Ubuntu. You don't need to change the space now allocated to D: .
Since Ubuntu can read and write NTFS, but Windows does not know how to read and write to ext4, leaving D: as is as a shared space for data used by both OS is a good idea.
Also, suggest you delay installing 19.10 as 20.04 is on the brink of release (tomorrow, 4/23); suggest you install 18.04 then upgrade to 20.04, or wait. Suggest you don't grab the beta of 20.04,, either do 18.04 now or wait until toomorrow's release of 20.04.
Turns out my older Ubuntu wasn't deleted. I rather had a problem with the Grub menu after updating Windows 10 to version 1909, which I fixed by installing boot-repair on a live session.