Question about probabilities?

Hello, i`d like to know why the probabilities From the image are:

Pr[Xk+1=1 | Xk=1]=0.5
Pr[Xk+1=2 | Xk=1]=0.5
Pr[Xk+1=1 | Xk=2]=0.2
Pr[Xk+1=2 | Xk=2]=0.8

Thank you so much
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