Nell collects baseball cards. She had 44 cards. She gave 22 cards to John and yet some more to Jeff. Now she has 1 cards left. How many cards did Nell give to Jeff?
Nell has 44 cards. 
Nell gives 22 cards to John. 
That means Nell has 44 - 22 = 22 cards left. 
Nell gives some more cards to Jeff. 
That means Nell has 22 - x = 1 card left, where x is the number of cards Nell gave to Jeff. 

We can solve this equation for x: 

22 - x = 1 
22 - 1 = x 
21 = x 

That means Nell gave 21 cards to Jeff.