comunicar red IPv4 (internal) - red IPv6 (external)

Good day to all

I am oscar de Colombia

where you come for a consultation and can advise me about a problem that I need uy being able to solve

the question is that I need to communicate networks, which are formed as follows, LAN (INTERNAL) is configured with IPv4 address but the link WAN (external) is IPv6 addressing, I have two teams mikrotik one RB951 and one RB751.

I hope you can give me a help