Nell collects baseball cards. She had 573 cards. She gave 195 cards to John and yet some more to Jeff. Now she has 210 cards left. How many cards did Nell give to Jeff?
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Nell had 573 cards. She gave 195 cards to John. So she has 573-195 = 378 cards left. 

Then she gave some more cards to Jeff. So she has 378-x cards left, where x is the number of cards she gave to Jeff. 

We know that 378-x = 210. So x = 378-210 = 168. 

Nell gave 168 cards to Jeff.