Answers

2015-08-09T10:55:12+08:00
The GCF of 15 and 30 :
15- 1,3,5,15
30- 1,2,3,5,10,.15,30

so the answer is 15

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2015-08-09T10:55:44+08:00
15,30,45,60,75,90 and more
30,60,90, and more 
:)
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