“workout noun a session of physical exercise or training. See also work out (sense 2) at work.”
“work out 1 to be successfully achieved or resolved • It'll all work out in the end. 2 to perform a set of energetic physical exercises • She's working out at the gym. See also workout.”
However, I have now learnt that ‘work out’ and ‘workout’ are interchangeable when referring to resolving or calculating. I am not sure if I know of any other word that can be split in two and retain the same meaning. (Note Collins insist on there being a hyphen as ‘work-out’)
It could be argued that the interchangeability is restricted to use as a verb and so EBS’s use is suspect but one would need a more qualified judge than yours truly for that.