Posted by **nicole** on Thursday, August 22, 2013 at 5:05am.

zac had some 2c stamps and some 5c stamps.He needed to put 30c on a postcard to mail it. What combinations of stamps could he use? would you please explain,thanks

- math -
**Reiny**, Thursday, August 22, 2013 at 7:32am
Assuming we can pay using either all 2¢ or 5¢ stamps...

let's start with

0 2¢ ----> 6 5¢

1 2¢ ----> leaves 28 ¢, can't be done with 5¢'s

..

5 2¢ ---> leaves 20 ¢, paid with 4 5¢

..

10 2¢ ---> 2 5¢

15 2¢ ---> 0 5¢

so in the form (2¢ , 5¢) we have

(0,6) , (5,4), (10,2), and (15,0)

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