EXTENSION CAB 1 X 12 FOR MK V COMBO, 4 OHM OR 8 OHM IN?

I've bought a MK V Combo and want to run it together with my Marshall 1 X 12 closed cabinet. Combo speaker and Marshall cabinet at the same time. The Marshall Cabinet is also 8 ohm

Do i have to put both speakers, the one inside the amp and the extension, in the 4 ohm jacks, or in the 8 ohm?

Read the manual and i think it is two times 4 ohm, but i'm not certain.

Searched for the answer on this forum but couldn't find it.

Thanks

you would put them both in the 4 ohm jacks.