[asharaf elgendy]

P1 V1 = P2 V2
8A X75 = 6A X P2
P2 = 100 cm.Hg
Addittional h of Hg = 100 - 75=25cm
but to raise the Hg 2cm in the left, the mercury will drop 2cm in the right so we have to add 4cm Hg to refill this difference in height
4 +25=29cm.Hg