I've just gone over this with a VCE maths student, so here...

I've just gone over this with a VCE maths student, so here goes!

BKW = Property + Building + 0.47SOL

SOL = Investments + 0.44BKW

Putting some guesstimates in the equation...

BKW property is worth 750m and building products about 350m

SOL's investments other than BKW are worth about 4400m

BKW = 750 + 350 + 0.47 SOL

SOL = 4400 + 0.44BKW

Using the scientific calculator...

BKW = 3994m (Current MC = 2448m)

SOL = 6157m (Current MC = 6600m)

Now,

BKW = 3994m = 750 + 350 + (0.47 x 6157)

and 

SOL = 6157m = 4400 + (0.44 x 3994)

Which suggests to me that if SOL's MC at 6600m is reasonable then BKW is seriously undervalued...