Kansas K-40 Line 13 - credit for taxes paid to other states

Hello, I have a similar situation to This link .  I did not find the process of filing kansas and missouri that intuitive for me, and I almost made a big mistake.  


I was prompted to enter the amount of income from the other state, when the state was already imported.  I left it blank initially.  I went back and just found the AGI for missouri.  When i did this my Kansas tax liability went down a good amount.  I just don't think I'm doing this section correct or putting the right amount in line 3 listed below.  Income derived is a weird description.  Any input is appreciated.

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