Yes it can because they both share a factor of 3 can be canceled.
6=3*2
15=3*5
3*2/3*5
cross out the 3
=2/5
Hope this helps.

Larraine328

Hello Rodguezmadison12,
6/15 can in fact be simplified.
Common factor is 3
6/3 =2
15/3=5
Final Answer is 2/5
~Naterator
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