migration VMs to new cluster

Dear all,

I have a 3 NODE Failover cluster running on windows 2008 R2 now I got 2 power full servers that I can run windows 2012 r2 server. How can I migrate my 25 VMs running on 2008r2 cluster to this new one running on windows 2012 r2?

Can someone help me or give me the faster and safest way to do it?

Regards,

nelson\

nelson chamba