brent Download and create Gparted USB disk from here, or if you have Solus on a USB drive you can use that, it will have gpartedon there.
The idea is to boot from USB, as you can't operate on the system partions when they are in use.
Now, boot from the USB stick, and in gparted: Move your first partition, /dev/sdc3 all the way to the left, and when that's completed move /dev/sdc1 all the way to the left.
The end result is your unallocated space is all consoldiated in one block to the right of the two partions you have just moved.
Usual cautions about having backups apply.
Edit: In fact if this is just an external drive, you can do it from within Solus without needed to boot from USB, you just need to right click and unmount the partitions before moving them. I was making things harder than they need to be! :-)
