At the factory a baseball card is places in every 9th cereal package a football card is placed in every 25th package what is the first package that gets both the baseball and football card

To figure out this question, look for the first number where both 25 and 9 are a factor of. 

25*1 is 25 which isn't a factor of 9, so it won't be 25.
25*2 is 50, which isn't a factor of 9.
75 is not a factor of 9. (you know because you don't get a whole number when you divide 75 into 9.)
100 is not a factor of 9, nor is 125, 150, 175, or 200.

However, 225 is a factor of both 25 and 9. This makes sense because 25*9 is 225. 

This means that the first package with both will be the 225th package.