100 Korun . I will be very exited if I find a way to exchange these bills
120 CZK is now around 5 USD, so it s really not that much. Another problem is that there was a revolution. What you have are Czechoslovakian bills, but since then the Czechoslovakia has dissolved into Czech Republic and Slovak Republic and I kinda doubt they would still exchange them more than 20 years after the dissolution
I agree, keep them as souvenirs. Even if you had current 120 crowns it would not be worth the trip to a bank to exchange the money.
They won't be exchangeable and of very little value.
Try your luck on Ebay, if you want to sell them.
Keep them for couple decades and you may sell them to someone who collects old artefacts ????
Sorry they are worthless.