You use the show version command to determine the software (firmware) version for both primary and secondary partitions of each installed module of the SLX device or of the SLX device itself.
For example, here is the output for SLX-OS 20.1.1.
device# show version
SLX-OS Operating System Version: 20.1.1
Copyright (c) 1995-2019 Extreme Networks, Inc.
Firmware name: 20.1.1
Build Time: 21:34:29 Nov 2, 2019
Install Time: 20:29:12 Nov 8, 2019
Kernel: 4.14.67
Control Processor: Intel(R) Atom(TM) CPU C3758 @ 2.20GHz, 8 cores
Microcode Version: 0x24
Memory Size: System Total: 15632 MB
System Uptime: 1days 1hrs 29mins 27secs
Name Primary/Secondary Versions
------------------------------------------
SLX-OS 20.1.1
20.1.1
device#