Let the cards be represented by = c
As given:
Number of cards Bob has = 51
Number of cards Bob gave away = 17
So, the number of cards 'c' left with Bob are =
[tex]c=51-17[/tex]
[tex]c=34[/tex]
This can also be written as :
[tex]c+17=51[/tex]
[tex]c=34[/tex]
So, total number of baseball cards left with Bob are 34.