Forty6and2SDMF

I'll be getting a Mesa Mark IV pretty soon (as soon as I can find one) and I want to run a 4x12 cab and a 2x12 at the same time. Theres an 8 ohm jack and (2) 4 ohm jacks on the back of the Mark IV. The 2x12 that Im looking at is 8 ohm but Im not sure what the 4x12 would be... My question is, how would I hook up (2) 8 ohm cabs to the Mark IV with only (1) 8 ohm jack and (2) 4 ohm jacks on the head?

Thanks!

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2012 Gibson Les Paul Classic Custom
2003 Gibson Les Paul Studio
Mesa Mark IV
Avatar Contemporary 6x12