Question 974845
Cookies are sold singly or in packages of 13 or 39. With this packaging, how many ways can you buy 78 cookies?
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The other tutor is wrong.
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You can buy 78 singles.
--> 78 1's
6 13's
2 39's
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1 39 and 3 13's
1 39, 2 13's and 13 1's
1 39, 1 13 and 26 1's
1 39 and 39 singles
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1 13 and 65 singles
2 13's and 52 singles
3 13's and 39 singles
4 13's and 26 singles
5 13's and 13 singles