Final answer:
John has 17 baseball cards.
Step-by-step explanation:
Let x be the number of baseball cards John has.
Cara has 8 times as many baseball cards as John, so Cara has 8x cards.
Together, Cara and John have 153 cards, so we can write the equation:
x + 8x = 153
Combining like terms, we get:
9x = 153
Dividing both sides by 9, we find that:
x = 17
Therefore, John has 17 baseball cards.
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