Anya's grandfather gives her a collection of souvenir subway tokens.

Question

Anya's grandfather gives her a collection of souvenir tokens.  He gives her 9 tokens from the 1960s, 12 tokens from the 1970s, and 21 tokens from the 1980s.  She wants to make a display of each type of token.  She wants all three displays to have rows with the same number of tokens in them.  How can she display the tokens?  

Answer 1

It looks like you are looking for the common factor for 9, 12, and 21.  What number can be divided into all three of those numbers and come out evenly.  That would be 3.

 

An array or chart of the tokens could be set up to prove that there would be 3 in each row.

 

1960s           X     X     X

                    X     X     X     (9 tokens in all)

                    X     X     X          3 times 3

 

1970s           X     X     X

                    X     X     X     (12 tokens in all)

                    X     X     X            3 times 4

                    X     X     X

 

1980s           X     X     X

                    X     X     X

                    X     X     X     (21 tokens in all)

                    X     X     X          3 times 7

                    X     X     X

                    X     X     X

                    X     X     X

      

I hope this explanation and chart helps you understand it better.  Laurie G.