Need help calculating knowledge gain change score

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Hello! I need to find the proportion of learners who felt they had knowledge gain postcourse – in terms of a positive change from before to after. However, the way the database spits out my data is a mess. Please see attached picture. Normally I would have pre score in one column and post score in the next column. I'd take the difference between pre/post for each individual. I'd then find the % of scores that are positive.

However, as you can see, this is more complicated in the data I have. This is just a sample, and a simplified sample at that. I have nearly 5k rows of data. Would anyone be willing to help me? I think this can be done with the data setup in the way it is, but I just don't know which code to use. Any help would be greatly appreciated. Thank you in advance!